If impeachment occurs and goes to the Senate does he really think he’s going to be able to weasel out of testifying?
Certainly not at the tribunal.
Yes.
An impeachment will only be delivered to the Senate if the Democrats have managed to line up guaranteed votes for conviction. Such proceedings would be merely a show trial and "due process" would be non-existent. The Democrats would be making the "rules" to insure the desired outcome.
They don't have those votes yet or they would have already started the proceedings.
What they are doing now is rallying their Leftist base and attempting to confuse the "independent" voters so they will tolerate the coup. Behind-the scenes they are making offers to Republican Senators who want to keep riding the gravy train. But if those Republicans have any sense, they must known they would be ending their political careers in exchange for promises which will never be delivered.
That last is a dicey expectation of course. Some Republicans really are stupid enough to fall for empty promises. Things could go either way.