If Google wanted - they could've easily released ChatGPT version that is 100x better than current one considering they invented the technology and they have thousands times more and better data to train it.
They just weren't interested.
I wouldn't be surprised if they used anonymized gmail data though. Even if they removed all proper nouns it'd probably provide a lot of extra tokens for training.
The impressive thing with chatGPT to me is how well it understand what you want even with very sparse input. Even if it gives wrong answers it still feels like you are both on the same page. That seems like the secret sauce even if a larger language model would give more correct output. I wouldn't be shocked at all if Google doesn't have anything currently that feels the way chatGPT does when it comes to interaction and now they are racing to build exactly that.
I don't think it's that, either, given the rate at which they are involved in overt censorship, over the last years.
I believe this tech is so different and revolutionary, that the lawyers have yet to wrap their head around it. I predict a million lawsuits incoming any time now. This I believe is the primary reason for Google not releasing any product before the water gets tested. For what its worth Google already has access to lots and lots of data that it owns, that it can train its AI on (Photos, Gmail, Docs, obviously Search and probably YouTube as well)
ChatGPT is very cool but they don't make money from it and GPT-3 had a paid public API for a year now and I read that the money they make from it is very little, insignificant compared to the funding they get from VCs.
Currently, there's no clear path for monetisation but has the capacity to take away a lot of Google's use cases. In essence, it's like Napster destroying the Music CD business.
Maybe it's also a bit like Kodak: Invents the technology but its current business is too good to be messed around with. This new tech is the future but we are happy in the moment.