We’re not the first ones to try to ask a voice actor if they have any involvement with Final Fantasy XV, but it does seems like one did reveal that they do.
Voice actor D.C. Douglas has a list of projects he has worked on as part of his resume listed on his official website. It just so happens that one of the games he has listed is Final Fantasy XV and is listed with a release date of “TBA 2016”.
Of course D.C. Douglas is no stranger to the world of voice acting as he has done voice over work for both anime and video games. Some of his video game credits include Gabi in.hack//G.U., Azrael in BlazBlue: Chronophantasma, Raven in the Tekken series, and most recently in Xenoblade Chronicles X as H.B.