They are on higher elevation then you, as they coming on top of that hill.Easy to spot you from there.Second , you are waiting for tank head on , not good thing IRL. Try positioning , so you are in his blind spot as it comes on the road. Also , as someone said 50-100 m distance( at 50 meters you are dead meat IRL) , not so good.At least that's what i am seeing there.
EDIT: I don't know if that counts in this game, but IRL is like this : The sun is directly on you , i base that on from your shadow, and you will have reflections of your gear. Other side is getting slightly in shadow while descending down that road, giving them advantage.FYI, modern tanks have automatic movement sensors (from personal experience i know that T-72 does), so if you even blink to hard they will register you from that distance, load and shoot in your direction within few seconds. I would think that is somehow reflected in game.