Well Kotaku is not exactly a credible source either. And she/he got everything right so far (teaser release date, boston, voiced main character and such...), plus that post was made 11 months ago.
It is fake. The hoaxer is claiming it will be a cross gen game; it won't be. The hoaxer is claiming it is an entirely new engine; It is not. The hoaxer even claims that they are the source of the Kotaku leak, and Kotaku says that is not true.
Everything that "leaker" has gotten correct so far was already widely speculated or rumored before the hoax leak was ever written by them. Boston. Voiced protagonist. E3 is a pretty good guess for an announcement date.
People do these all the time on 4chan/reddit. Claiming to be some leaker with information about a highly anticipated game. They parrot some details that are already rumored or speculated by the community and add a few additions of their own while never offering any proof what they say is true (because they don't have any proof because they are making shit up). They are always proven to be incorrect and hoaxes. Given how often they occur some of those hoaxes are gonna get some of the details right some of the time.