Holland have enjoyed a hugely successful qualifying campaign, winning eight of their nine matches in Group D ahead of this evening's final fixture in Istanbul.
Turkey need a win this evening to claim second spot and a playoff place, with Romania level on points ahead of their clash with Estonia.
With Turkey desperate for three points Van Gaal has declared that the intense atmosphere in Istanbul will provide his young squad with a stern test, with the Oranje coach adamant that he still expects to win.
He told reporters: "It will be interesting to see how the guys will deal with it. That's why this game is also important for us. The environment in Brazil will be the same.
"The football fans in Turkey are incredible. As a player I loved that. I had no problems with that. I think the players also. But we will actually know that tomorrow."
"I said that already after our first game against Turkey, they are the best after Holland in our group. On the other hand, I could be wrong in the end. Because we really want to defeat Turkey to get points for the FIFA ranking."
Holland are unbeaten in their last 31 qualifying matches, a run they extended by beating Hungary 8-1 last Friday.