I just asked get ChatGPT a question about use of language in a specific book (China Miéville's Kraken). It gave a plausible answer but used a common English word ('knackering') instead of the word 'knacking' that is actually used (the word 'knackering' isn't in the text). I then asked it to give me a quote using 'knackering' and it gave me a quote with the word 'knacking'. I asked it to put the quote into Harvard reference style which it did, but didn't provide a page number, which it said I'd have to look up myself.
I think relying on ChatGPT for an essay would be fairly frustrating, and if you used ChatGPT to develop your thesis, you could very quickly get a generic plagiaristic answer (based on the quotes everyone else used) rather than one than that captured your own response to the text, and which contained factual errors.
[Edit] It also said that "gods inhabiting USB sticks are presented matter-of-factly" in Kraken which is false (there are no mentions of USB). When I asked it for a quote to support its assertion, it replied "While the novel doesn't explicitly depict gods inhabiting USB sticks..."