The Apostle Peter was familiar with the Apostle Paul's letters (2 Peter 3, NKJV):
14 Therefore, beloved, looking forward to these things, be diligent to be found by Him in peace, without spot and blameless; 15 and consider that the longsuffering of our Lord is salvation—as also our beloved brother Paul, according to the wisdom given to him, has written to you, 16 as also in all his epistles, speaking in them of these things, in which are some things hard to understand, which untaught and unstable people twist to their own destruction, as they do also the rest of the Scriptures.
We know that most if not all of the NT writers knew each other and crossed paths frequently - in Jerusalem, in Antioch, and from time to time elsewhere (read Acts). It is impossible to imagine that they would be unaware of each other's ministry, including their letters, their Gospels, and St Luke's history (Acts). The Revelation was likely written towards the end of the Apostle John's life, and since he was the last to die, that would be an exception.