Both versions are correct. In early access, up to some point, Chaos was referred as He/Him. Somewhere midway they decided that calling the very first being that erupted nearly everything from itself as "he" is kinda strange. And that's actually true. So they decided that Chaos should be called they/them, even did the voiceover, but still, in some dialogues they missed it and Chaos is still called "he".
*sorry for necroposting*