There's just no good result from one of these interviews. It's no mistake that "lying to the FBI" has been the charge in the two revealed indictments. It's no mistake that Clinton's answers were pretty much always some version of "not to my recollection."
If he's going to do this interview, under oath or otherwise, I'd advise that he not given any definitive answer. For all you know, they have two recordings that appear to conflict, and will use which ever one you don't endorse as proof of a lie.
On the other hand, he's been deposed before, and I honestly don't believe he has anything to hide on the whole Russian manipulation point.
It's unclear if he's coachable. Certainly he's been deposed before, but in civil matters that can generally just become more negotiating if he weakens his case. The good that could come of it would come from full disclosure, not something that his staff have been very good at. They get caught in something and they quibble it away "that wasn't important" or "I forgot"
I have an electronic calendar going back years. If I were going to be deposed about people I met with, I'd scrub it down with a fine comb and name anything remotely relevant.
For Trump, he'd likely say, "I never discussed the matter in any way shape or form." Then you get Carter Page and others taking a plea and revealing "oh sure, we talked about it". Thus the "not to my recollection" or "not to my knowledge" boilerplate responses. That's not Trump's way of talking. Even if he were coached, I suspect based on some public interviews, he would chafe and get so irate everything would blow out the window.
Bill Clinton got caught in his trickery over whether the affair was past or present tense. As if anyone were asking as of right that moment. "No, I am not having sexual relations with that woman right this very moment."
But Trump has "one of the greatest memories of all time" and "the best words" - which doesn't leave a lot of room for "I forgot" or "I misunderstood".
He's randomly bragged that he met Putin in the past - recorded on Letterman and otherwise.
So have they
met or not?
The only way out of that line of questioning is to admit that he was lying all those other times about meeting Putin to make himself look grand, or to admit that he had met a number of times and then have to enumerate them and what he discussed.