Then I saw an angel coming down from heaven, holding the key of the abyss and a great chain in his hand. And he laid hold of the dragon, the serpent of old, who is the devil and Satan, and bound him for a thousand years; and he threw him into the abyss, and shut it and sealed it over him, so that he would not deceive the nations any longer, until the thousand years were completed; after these things he must be released for a short time.[Revelation 20:1-3]
So, we see a lot of figurative language used. Satan depicted as a dragon. Is he literally a dragon? No, of course not. Was he literally wrapped in chains. No. So why take the 1,000 years literal?
How about this verse?
Know therefore that the Lord your God, He is God, the faithful God, who keeps His covenant and His lovingkindness to a thousandth generation with those who love Him and keep His commandments;[Deuteronomy 7:9]
Is God faithful to a literal 1,000th generation? He could be, and if He is, then the world will be anywhere from 25,000 to 40,000 years old, seeing that a biblical generation was somewhere between 25 and 40 years. I’ve heard both so I don’t know which one is correct, but I think 40 to be the correct one, seeing Israel was in the wilderness for 40 years after leaving Egypt and entering into the Promised Land.