a) the human would (deservedly[1]) be arrested for manslaughter, possibly murder
b) OpenAI would be deeply (and deservedly) vulnerable to civil liability
c) state and federal regulators would be on the warpath against OpenAI
Obviously we can't arrest ChatGPT. But nothing about ChatGPT being the culprit changes 2) and 3) - in fact it makes 3) far more urgent.
[1] It is a somewhat ugly constitutional question whether this speech would be protected if it was between two adults, assuming the other adult was not acting as a caregiver. There was an ugly case in Massachusetts involving where a 17-year-old ordered her 18-year-old boyfriend to kill himself and he did so; she was convicted of involuntary manslaughter, and any civil-liberties minded person understands the difficult issues this case raises. These issues are moot if the speech is between an adult and a child, there is a much higher bar.
One first amendment test for many decades has been "Imminent lawless action."
Suicide (or attempted suicide) is a crime in some, but not all states, so it would seem that in any state in which that is a crime, directly inciting someone to do it would not be protected speech.
For the states in which suicide is legal it seems like a much tougher case; making encouraging someone to take a non-criminal action itself a crime would raise a lot of disturbing issues w.r.t. liberty.
This is distinct from e.g. espousing the opinion that "suicide is good, we should have more of that." Which is almost certainly protected speech (just as any odious white-nationalist propaganda is protected).
Depending on the context, suggesting that a specific person is terrible and should kill themselves might be unprotected "fighting words" if you are doing it as an insult rather than a serious suggestion (though the bar for that is rather high; the Westboro Baptist Church was never found to have violated that).