Relative to his level of fame, his actual level of contribution as far as pushing forward AI, I’m not so sure about.
I deeply appreciate his educational content and I’m glad that it has led to a way for him to gain influence and sustain a career. Hopefully he’s rich enough from that that he can focus 100% on educational stuff!
He did pioneering research in image captioning - aligning visual and textual semantic spaces - the conceptual foundation of modern image generators. He also did an excellent analysis of RNNs - one of the first and best explanations of what happens under the hood of a language model.