In order to live BT needs sacrifices. Durind to the Forced text, does he need one sacrifice from each player to live or is it ok if only i have a unit in the same zone as the BT or if only my opponent has a unit in the corresponding zone?

Bloodthirster doesn't need sacrifices to live. But if he is in play, both players are forced to sacrifice one unit in their corresponding zones. If your opponent doesn't have a unit in that zone, he simply cannot sacrifice one, but nothing else happens. But if you have only Bloodthirster in your zone, you have to sacrifice him.