I don't know if Springmeier is merely conjecturing or knows more. He puts a lot of faith in these people who contact him saying they are former illuminati/satanists and revealing secrets. Though such evidence is hardly solid, it's probably the only sort of evidence that's ever likely to go public from such circles.

As to Dali he was definitely close to some of the Rothschilds. It could be his transition from atheist to Christianity was an act, part of his persona for the art world. I don't know enough about the man.