Frankly, the outcome of this FBI investigation could also be that the administration is cleared in the end.
At this point, if he wants to ever be an effective President (doubtful), Trump
needs the FBI investigation to clear him, so that he can move past Russiagate. That he and his supporters are not confident that an investigation (by the man who more than any other individual handed Trump the Presidency, no less) will clear Trump says volumes. His followers think he's guilty (not that they'll admit it), and he and his cronies obviously have things they want to keep hidden.
Trump's clumsy, desperate-looking pushback and maneuvering against the Congressional and DoJ investigations is what convinces me that he is guilty, more than anything else.