Overdrive 2 and the Nintendo doc seem rather iffy to me as well. As for Elder Scrolls 6, I dunno if he's actually teasing it. Even if he is, Starfield is a trademark owned by Zenimax meaning it could be developed by any of their studios, not just Bethesda Softworks. A ResetEra insider has plenty more credibility than this guy as it stands right now though.
Lots of times these "leakers" will embed one nugget of truth in with a bunch of BS in order to pass off the BS stuff as being real as well. For instance, just a few weeks ago there was a leaker who knew the exact date that Nintendo would announce details for Switch's online service. However, several other things from his leak have since been proven untrue. For instance, he said the Sonic Racing game would be announced at Nintendo's E3 conference and would feature Sonic on foot with some other character in Karts, that part was confirmed fake today, as Sonic is in a kart just like the rest of the characters.