Although Anne is pleasantly surprised at how well her first evening at Camden Place passes, I don't think she's curious enough about Mr Elliot to draw an actual conclusion. There's an unsolved mystery...

Ch15> Still, however, she had the sensation of there being something more than immediately appeared, in Mr. Elliot's wishing, after an interval of so many years, to be well received by them.

...and she comes up with one possible explanation, with an 'if' in it. By the way, does Mr Elliot's ch16 speech, in favour of not being too fastidious, amount to some support for the theory that he admires Elizabeth? Or would that require more unfastidiousness than he meant?

What else do we know about him? He admired Anne in passing at Lyme**, but without knowing who she was, and was already calling repeatedly at Camden Place before she got there. He's being very courteous toward Sir Walter, and disapproves of Mrs Clay. I don't think we've got enough to go on with any certainty.