If Wikipedia can be believed, and I have actually never seen anything anywhere to say that he is, Jonathan Cahn is not a Rabbi, even though he calls himself that. According to above link, it says Pastor/rabbi....(I don't know/think that is exactly the same?)
It was only after he wrote his first book, "The Harbinger" which is not at all correct as far as he sees it, that he started to call himself a Rabbi.
I actually can't understand how such people as Jan Markell and others seem to think he is so fantastic.... have a look at this
here and see what you think?