Sam mentioned on several occasions that GPT-5 will be much smarter than GPT-4. On Lex Fridman’s podcast, he even said the gap between GPT-5 and 4 will be as wide as GPT-4 and 3 (not 3.5).
He did remain silent on when it’s going to be launched.
OpenAI has been open about their ability to predict model performance prior to training. When Sam talks about GPT-5 he could very easily be talking about the hypothetical performance of a model given their internal projections. I think it’s very unlikely a fully trained GPT-5 exists yet.
