I think they're close enough that it depends on your use case. IME, which is mostly generating Python and shell code, Gemini Advanced is faster, less lazy and generates overall better solutions than GPT-4. It also seems to be more up-to-date with libraries and stuff. It can also directly go to URLs (e.g. summarise a paper), which GPT-4 refuses to do.
Gemini Ultra scored 90% which is better than GPT-4.
This reads like a paid-for press release from Microsoft to pretend like they're almighty and Google is incompetent.