Uhh, the first line literally says (to quote) "Saiko No Sutoka is a Horror Survival Game". Both "Horror" and "Survival" are there.
I think you're mistaking the wording as meaning something else: if it was a pure Survival game then the Horror term wouldn't be added. As far as definitions and gameplay, this follows the same principles as a game like Alien: Isolation since you have little/no way to fight against your adversary while they can (easily) kill you, for example. Survival might be the "Parent Genre" but Survival Horror is specific to this style of "Survival" games: induce fear, offer a feeling of powerlessness, solve a set of puzzles to progress and avoid your adversary as much as you can.