The Australian-registered website posted Evolve on its pre-order page with the release date marked at 5 September 2014. While the leak might be for the PS4, the Xbox One and PC version are expected to share the same date.
On the other hand, the cited release date might just be a placeholder and awaiting a confirmation by the game developer.
One thing is for sure and it is that Evolve is currently in its final stages of development by the same team that brought us the Left 4 Dead series. All that is left to do is wait for future announcements, or simply hope for the 5 September date to be true.