There's no automated way, so the best/easiest thing to do is to search for the reference e.g. in google scholar (you can do that with the google scholar browser add-on, e.g., or just manually) and import into Zotero from there or by following the link.
That's also a good idea because a) ChatGPT does not actually "cite" things -- it creates strings that plausibly look like references, but often don't actually exist (you can find thousands of examples of this on social media). You'll want to verify the existence of a work before adding it to Zotero and b) While some of ChatGPT's summaries of academic works are OK, others are completely off. You'll want to verify whatever the AI claims before using it in academic or school work of any kind.
As adamsmith wrote: do not use Chat GPT as a source of references. This Chatbot is trained to provide "believable" answers, not correct answers. Many documents, which were cited by Chat GPT, do not exist in reality.
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That's also a good idea because
a) ChatGPT does not actually "cite" things -- it creates strings that plausibly look like references, but often don't actually exist (you can find thousands of examples of this on social media). You'll want to verify the existence of a work before adding it to Zotero and
b) While some of ChatGPT's summaries of academic works are OK, others are completely off. You'll want to verify whatever the AI claims before using it in academic or school work of any kind.