I just got FFF at WWE. I read his rules carefully and did not see any mention of him being immune to outwit. Does anyone know if FFF is vulnerable to outwit?

Depends.

In the Scenario version, he has the Power Cosmic TA (says so right in the Scenario rules) and is thus immune to Outwit.

In the Force version, he has no TA and is not listed as being immune to Outwit in the list of immune powers. Outwit away.