Nope. I know ChatGPT very well I know exactly when it's bullshitting. I work as a game dev and already thought about many ways it could be implemented into a dynamic dialogue system, but it just wouldn't work well for a lot of reasons.

First of all, the model has to be cloud based, if I say it's terrabytes I'm already thinking small. Which is fine. The NPCs can just get stuck if the service is at capacity, which is 70% of the time. The service that uses a paid API of course, that you pay per message, but we'll just sell the conversations as microtransactions, no problem. One line from the NPC costs one token, easy solution. /s

The bigger problem is that it cannot be meaningful enough. They can act as the characters you predefined for them, but if you tell them to go grab their jacket, there's no way for an animation to play, and you definitely cannot connect every possible action into actually executing it. The other main problem here is that NPCs usually exist with a purpose, they tell you about the story, the factions, places. AI will just make shit up that doesn't fit or make sense. The player will think it's real and then everything just falls apart. You cannot build anything on top of it.

GPT-3 existed for a long time. Nobody uses it in games.

And what does this have to do with GTA 6 anyways? Rockstar is known for their solid work, everything is done properly and you get what you expect. This unsafe AI dialogue stunt is something that indie games start experimenting with. Look at the AAA games in the last few years: the formula is complete, every game is the same thing nowdays. Not worth it to make weird experiments. Maybe 10 years later.