The name John in Revelation 1:1 links the seer up with John the Baptist, the messenger who came from God to announce the coming of Christ. Some (JM Ford,Revelation (The Anchor Bible, Vol. 38)) have suggested that this points to John the Baptist and his circle as the source of the gospel. Thats mistaken, but I think the allusion is there, and many of the themes of Revelation recapitulate themes that arise at the beginning of Jesus ministry.
John the Baptist comes from God (1:6), and John the seer receives the unveiling from Jesus and His angel (1:1). John the Baptist is a ??????? in order to ????????? (John 1:7), and John the seer is also said to witness the witness of Jesus (emarturesen . . . ten marturian). John the Baptist testifies to the Pharisees that he is not Elijah nor the Prophet, but that he comes to disclose through baptism the One who stands hidden among them (John 1:26-27). John the Baptist calls Jesus the Lamb of God (John 1:29, 36), and John the seer sees a Lamb ascend to heaven to receive the book from God (Revelation 4). John the Baptist calls Jesus the Bridegroom (John 3:27) and speaks of himself as a friend of the bridegroom. Belief in the Son leads to eternal life, but disbelief brings the wrath of God (John 3:36).
John the Baptist was the forerunner to Jesus, who unveiled Him in His earthly ministry. John the Seer is the forerunner to Jesus, unveiling Him in His coming again. This is another reason to read Revelation and John’s gospel together.