Holland celebrated their qualification for the finals in Brazil with a solid 2-0 win that finally ended Turkey's tame challenge for a play-off place.
Fatih Terim's men needed to beat the Group D winners while hoping rivals Romania dropped points.
But an early free-kick from Arjen Robben put Turkey firmly on the back foot and Wesley Sneijder's goal shortly after the break confirmed the win.
Holland's early goal drained much of the hope among the home fans and Van Gaal was delighted that his players stood tall in the Istanbul cauldron.
"If you can get a stadium quiet and you leave to the applause of the opponents' fans, that's fantastic. That says a lot about how we played," Van Gaal told Voetbal International.
It was a ninth win in 10 qualifying games for Holland but Turkey finished a poor fourth behind Romania and Hungary after both nations won their respective games against Estonia and Andorra.
In a game which featured a Holland side fresh from hammering Hungary 8-1 and a Turkey team desperate to secure second place, it was remarkable that the first 20 minutes produced only one shot on goal - albeit one which brought the opening goal.
In the eighth minute, Hasan Ali Kaldirim felled Robben as he loped towards the penalty area and the Bayern Munich winger promptly showed his gratitude by firing home the resulting free-kick.
And, immediately after the restart, Galatasaray midfielder Sneijder hurt his host city with the second goal of the night to finally kill off Turkish hopes.
Van Gaal felt his side's display was worthy of a bigger margin of victory.
"I am proud of my team," he told Dutch broadcaster SBS6.
"There are not many teams that come here and find it easy. I just wish that we had scored more, especially after the break.
"We are clearly on the right track. We have made progress in possession and that is reflected in the result."
With Van Gaal painting an optimistic picture for the 2010 World Cup runners-up, it fell to Robben to sound a note of caution.
"We are not favourites for the World Cup but we are improving," he said.
"We must look at ourselves, not at other countries.
"I think we are improving step by step. But there is still a lot of work to do. We need to remain calm and stay with both feet on the ground."