They definitely didn't train their own model; there are only a few places in the world that can do that and Gab isn't one of them. Almost every one of these bots, as I understand it, is a frontend over one of the main models (usually GPT or Mistral or Llama.)

I only spent a short time with this one but I am pretty confident it's not GPT-4. No idea why that part is in the prompt; maybe it's a leftover from an earlier iteration. The Gab bot responds too quickly and doesn't seem as capable as GPT-4 (and also, I think OpenAI's content filters just wouldn't allow a prompt like this.)