Thanks much. Wow these sources are really ultra kooks. It's just one hoax after another. They made up that the Gnostics were oversexed orgy hunters. A fiction dismantled back in the 1960s when the Nag Hammadi library was found.
They're also making up that "prostitution" happened in pagan temples. This was dismantled by classics scholars back in the 1960s but Christian sources continue to repeat the lies. (Cf. "The Myth of Sacred Prostitution in Antiquity" by Stephanie Lynn Budin.) Please inform Christians that pagan deities were devoted to sexual regulations! Artemis was the goddess of chastity!!
The sources you cite try to work the single word "porneia" into a case that Jesus is here to regulate sex. But porneia clearly means idolatry.
Epiphanes was a young Christian writer and I don't know that he was Gnostic. He did argue that "free love" was an extension of the Jesus teachings. But Epiphanes lived in the 2nd century, so he is certainly not being referenced in Revelation, which seems to have been written around 50 A.D.