Board Thread:Lore Discussion/@comment-10407900-20140914234758/@comment-5632187-20140915024040

"officially confirmed" cite dat source.

Gwyn is found hollowed in the Kiln of the First Flame, meaning he's been affected by the Undead curse. He can't be a god, as being a god would mean that he's too powerful to die. The fact of the matter is that you give up Humanity when you strengthen the fire. That's actual fact, confirmed by in-game descriptions and mechanics.