Revelation often uses numerals in a symbolic manner. John mentions four angels holding back the four winds of the earth (Rev. 7:1-4). Is this depiction literal or figurative? Four angels release a calvary from the great river Euphrates and a woman in heaven is seen with a crown of twelve stars on her forehead (Rev. 9:13-19; 12:1ff). Are these references literal? They are apparently symbols in light of Rev. 1:1 and other passages like Rev. 12:1 which explicitly identify some references as signs. Individual persons are employed at times to signify groups of people or inanimate entities in the Bible. For example, it's possible that the woman in 12:1 symbolizes a group of persons and not an individual woman in heaven. We also read about four living creatures and 24 elders (Rev. 4:1-11) in the so-called "throne-room vision."
However, I concede the point that not everything in Revelation is symbolic. What one views as literal or symbolic is often governed by his or her theology although context should also be a strong determining factor. While I may believe that Satan's torment is symbolic, others understand his torment to be literal, but then inconsistently claim that Rev. 20:14-15 and its mention of death and hades being cast into the lake of fire is at least partly--if not completely--symbolic. In the final analysis, I would submit that Scripture as a whole and our understanding of God's nature must also govern our understanding of Revelation.
The Bible indicates that Satan and all those who follow him will be eternally destroyed or annihilated (Matt. 7:13, 14; 2 Thess. 1:9; Rev. 17:8). Furthermore, I wonder how a God of love could torment sentient and rational beings for all eternity (1 John 4:8). Additionally, if we construe a number of the symbols literally in Revelation, then it seems to makes nonsense of the book and possibly makes a liar out of John.
GRB Murray said it best in his commentary on Revelation, when he noted that John writes: "with parables and symbols which point to ideas beyond their verbal expression" (Murray 299). Therefore, we have to be careful when we conclude that God is going to torture people in a literal lake of fire for all eternity. Other verses show that God will bring evildoers to a fitting end by annihilating them forever (Ps. 145:20; Isa. 66:24).