An update from https://bitcointalk.org/index.php?topic=3032215.0;all :

Jeff Garzik is one of the few people who had private email contacts with Satoshi Nakamoto and Jeff Garzik has agreed with me that Dave Kleiman probably was Satoshi Nakamoto. In a Bloomberg interview Jeff has said "My personal theory is that it’s Floridian Dave Kleiman, It matches his coding style, this gentleman was self taught. And the Bitcoin coder was someone who was very, very smart, but not a classically trained software engineer.”
https://www.bloomberg.com/news/articles/2018-11-08/bitcoin-pioneer-who-gave-away-over-100-million-has-no-regrets

I also see that most people who have been in contact with Satoshi Nakamoto in the early days of bitcoin, people like Hal Finney and Jeff Garzik, seemed to think that they were dealing with a single person and not with a group of persons.