One wonders where Bill Gates read that superintelligent AI could be (but in his estimation, in fact isn't) a GCR. It couldn't have been Kurzweil, because Kurzweil doesn't say that. The only realistic possibilities are that the influence came via Nick Bostrom, Stephen Hawking or Martin Rees or possibly Bill Joy(See comments).
The idea is also quite common in Science Fiction.
Or reading OvercomingBias (unlikely), or talking to someone who did (more likely) - my impression is that more people may have been in contact with the "Scary Idea" though Eliezer's writing than through that of the other people you list (except probably Kurzweil). Back when Eliezer was posting daily on OB, I'd see mentions of the blog from quite varied sources (all quite geeky).
Of course, still more people have been exposed to a form of the Scary Idea through the Terminator movies and other works of fiction.
Gates could have come up with the idea by himself, too.
"There are other potential problems in the future that Mr. Ridley could have addressed but did not. Some would put super-intelligent computers on that list. My own list would include large-scale bioterrorism or a pandemic ... But bioterrorism and pandemics are the only threats I can foresee that could kill over a billion people."
- Bill Gates
From
Africa Needs Aid, Not Flawed Theories
One wonders where Bill Gates read that superintelligent AI could be (but in his estimation, in fact isn't) a GCR. It couldn't have been Kurzweil, because Kurzweil doesn't say that. The only realistic possibilities are that the influence came via Nick Bostrom, Stephen Hawking or Martin Rees or possibly Bill Joy(See comments).
It seems that Bill is also something of a Bayesian with respect to global catastrophic risk:
"Even though we can't compute the odds for threats like bioterrorism or a pandemic, it's important to have the right people worrying about them and taking steps to minimize their likelihood and potential impact. On these issues, I am not impressed right now with the work being done by the U.S. and other governments."