Irenaeus claims the following:
(1) There will be an Antichristbefore the end of the world.
(2) Believers will suffer intense persecution in this Great Tribulation (perhaps he was thinking that the persecution they were undergoing at the hands of the Romans was this Great Tribulation).
(3) After this, believers will be "caught up" (rise from the dead) into a renovated creation to enjoy the blessings which include tremendous crops of fruit.
He does not mention anything about a 1,000 yearmillennium (although he doesn't say anything to refute it either).
To use Irenaeus as a support for premillennialism is very weak since he doesn't specifically address it.
Irenaeus Against Heresies - Book V
Chapter XXIII — The Devil is Well Practised in Falsehood, By Which Adam Having Been Led Astray, Sinned on the Sixth Day of the Creation, in Which Day Also he Has Been Renewed by Christ
Now in this same day that they did eat, in that also did they die. But according to the cycle and progress of the days, after which one is termed first, another second, and another third, if anybody seeks diligently to learn upon what day out of the seven it was that Adam died, he will find it by examining the dispensation of the Lord. For by summing up in Himself the whole human race from the beginning to the end, He has also summed up its death.
From this it is clear that the Lord suffered death, in obedience to His Father, upon that day on which Adam died while he disobeyed God. Now he died on the same day in which he did eat. For God said, "In that day on which ye shall eat of it, ye shall die by death."
The Lord, therefore, recapitulating in Himself this day, underwent His sufferings upon the day preceding the Sabbath, that is, the sixth day of the creation, on which day man was created; thus granting him a second creation by means of His passion, which is that [creation] out of death. And there are some, again, who relegate the death of Adam to the thousandth year; for since "a day of the Lord is as a thousand years," he did not overstep the thousand years, but died within them, thus bearing out the sentence of his sin.
Whether, therefore, with respect to disobedience, which is death; whether [we consider] that, on account of that, they were delivered over to death, and made debtors to it; whether with respect to [the fact that on] one and the same day on which they ate they also died (for it is one day of the creation); whether [we regard this point], that, with respect to this cycle of days, they died on the day in which they did also eat, that is, the day] of the preparation, which is termed "the pure supper," that is, the sixth day of the feast, which the Lord also exhibited when He suffered on that day; or whether [we reflect] that he (Adam) did not overstep the thousand years, but died within their limit,—it follows that, in regard to all these significations, God is indeed true.
For they died who tasted of the tree; and the serpent is proved a liar and a murderer, as the Lord said of him: "For he is a murderer from the beginning, and the truth is not in him."
1. Inasmuch, then, as in this world some persons betake themselves to the light, and by faith unite themselves with God, but others shun the light, and separate themselves from God, the Word of God comes preparing a fit habitation for both. For those indeed who are in the light, that they may derive enjoyment from it, and from the good things contained in it; but for those in darkness, that they may partake in its calamities.
And on this account He says, that those upon the right hand are called into the kingdom of heaven, but that those on the left He will send into eternal fire for they have deprived themselves of all good
2. And for this reason the apostle says: "Because they received not the love of God, that they might be saved, therefore God shall also send them the operation of error, that they may believe a lie, that they all may be judged who have not believed the truth, but consented to unrighteousness."
For when he (Antichrist) is come, and of his own accord concentrates in his own person the apostasy, and accomplishes whatever he shall do according to his own will and choice, sitting also in the temple of God, so that his dupes may adore him as the Christ; wherefore also shall he deservedly "be cast into the lake of fire": [this will happen according to divine appointment], God by His prescience foreseeing all this, and at the proper time sending such a man, "that they may believe a lie, that they all may be judged who did not believe the truth, but consented to unrighteousness;" whose coming John has thus described in the Apocalypse:
After this he likewise describes his armour-bearer, whom he also terms a false prophet:
Let no one imagine that he performs these wonders by divine power, but by the working of magic. And we must not be surprised if, since the demons and apostate spirits are at his service, he through their means performs wonders, by which he leads the inhabitants of the earth astray.
John says further: "And he shall order an image of the beast to be made, and he shall give breath to the image, so that the image shall speak; and he shall cause those to be slain who will not adore it." He says also: "And he will cause a mark [to be put] in the forehead and in the fight hand, that no one may be able to buy or sell, unless he who has the mark of the name of the beast or the number of his name; and the number is six hundred and sixty-six," that is, six times a hundred, six times ten, and six units. [He gives this] as a summing up of the whole of that apostasy which has taken place during six thousand years.
3. For in as many days as this world was made, in so many thousand years shall it be concluded. And for this reason the Scripture says: "Thus the heaven and the earth were finished, and all their adornment. And God brought to a conclusion upon the sixth day the works that He had made; and God rested upon the seventh day from all His works."
This is an account of the things formerly created, as also it is a prophecy of what is to come. For the day of the Lord is as a thousand years; and in six days created things were completed: it is evident, therefore, that they will come to an end at the sixth thousand year.
5. And therefore throughout all time, man, having been moulded at the beginning by the hands of God, that is, of the Son and of the Spirit, is made after the image and likeness of God: the chaff, indeed, which is the apostasy, being cast away; but the wheat, that is, those who bring forth fruit to God in faith, being gathered into the barn.
And for this cause tribulation is necessary for those who are saved, that having been after a manner broken up, and rendered fine, and sprinkled over by the patience of the Word of God, and set on fire [for purification], they may be fitted for the royal banquet. As a certain man of ours said, when he was condemned to the wild beasts because of his testimony with respect to God: "I am the wheat of Christ, and am ground by the teeth of the wild beasts, that I may be found the pure bread of God."
Chapter XXIX — All Things have been Created for the Service of Man. the Deceits, Wickedness, and Apostate Power of Antichrist. this was Prefigured at the Deluge, as Afterwards by the Persecution of Shadrach, Meshach, and Abednego.
1. In the previous books I have set forth the causes for which God permitted these things to be made, and have pointed out that all such have been created for the benefit of that human nature which is saved, ripening for immortality that which is [possessed] of its own free will and its own power, and preparing and rendering it more adapted for eternal subjection to God.
And therefore the creation is suited to [the wants of] man; for man was not made for its sake, but creation for the sake of man.
Those nations however, who did not of themselves raise up their eyes unto heaven, nor returned thanks to their Maker, nor wished to behold the light of truth, but who were like blind mice concealed in the depths of ignorance, the word justly reckons "as waste water from a sink, and as the turning-weight of a balance—in fact, as nothing;"
(1) so far useful and serviceable to the just, as stubble conduces towards the growth of the wheat, and its straw, by means of combustion, serves for working gold. And therefore, when in the end the Church shall be suddenly caught up from this, it is said, "There shall be tribulation such as has not been since the beginning, neither shall be."
(2) For this is the last contest of the righteous, in which, when they overcome they are crowned with incorruption.
2. And there is therefore in this beast, when he comes, a recapitulation made of all sorts of iniquity and of every deceit, in order that all apostate power, flowing into and being shut up in him, may be sent into the furnace of fire. Fittingly, therefore, shall his name possess the number six hundred and sixty-six, since he sums up in his own person all the commixture of wickedness which took place previous to the deluge, due to the apostasy of the angels.
For Noah was six hundred years old when the deluge came upon the earth, sweeping away the rebellious world, for the sake of that most infamous generation which lived in the times of Noah. And [Antichrist] also sums up every error of devised idols since the flood, together with the slaying of the prophets and the cutting off of the just.
For that image which was set up by Nebuchadnezzar had indeed a height of sixty cubits, while the breadth was six cubits; on account of which Ananias, Azarias, and Misael, when they did not worship it, were cast into a furnace of fire, pointing out prophetically, by what happened to them, the wrath against the righteous which shall arise towards the [time of the] end.
For that image, taken as a whole, was a prefiguring of this man's coming, decreeing that he should undoubtedly himself alone be worshipped by all men. Thus, then, the six hundred years of Noah, in whose time the deluge occurred because of the apostasy, and the number of the cubits of the image for which these just men were sent into the fiery furnace, do indicate the number of the name of that man in whom is concentrated the whole apostasy of six thousand years,and unrighteousness, and wickedness, and false prophecy, and deception; for which things' sake a cataclysm of fire shall also come [upon the earth].
Chapter XXXIII — Further proofs of the Same Proposition, Drawn From the Promises Made by Christ, When he Declared that he Would Drink of the Fruit of the Vine with his Disciples in his Father's Kingdom, While at the Same Time he Promised to Reward Them an Hundred-fold, and to Make Them Partake of Banquets. The Blessing Pronounced by Jacob had Pointed Out this Already, as Papias and the Elders have Interpreted it.
3. the righteous shall bear rule upon their rising from the dead; when also the creation, having been renovated and set free, shall fructify with an abundance of all kinds of food, from the dew of heaven, and from the fertility of the earth: as the elders who saw John, the disciple of the Lord, related that they had heard from him how the Lord used to teach in regard to these times, and say: The days will come, in which vines shall grow, each having ten thousand branches, and in each branch ten thousand twigs, and in each true twig ten thousand shoots, and in each one of the shoots ten thousand dusters, and on every one of the clusters ten thousand grapes, and every grape when pressed will give five and twenty metretes of wine. And when any one of the saints shall lay hold of a cluster, another shall cry out, I am a better cluster, take me; bless the Lord through me. In like manner [the Lord declared] that ... all animals feeding [only] on the productions of the earth, should [in those days] become peaceful and harmonious among each other, and be in perfect subjection to man.
"For the day of the Lord is as a thousand years; and in six days created things were completed; it is evident, therefore, that they will come to an end at the sixth thousand years."