Bayern, level on points with Bundesliga leaders Bayer Leverkusen and at home to Borussia Dortmund on Saturday, have reached an important point in a season which started slowly but has gathered momentum since November.
Also on Saturday, unbeaten Leverkusen are at home to champions VfL Wolfsburg who are in freefall and are without a win in 11 games in all competitions.
Van Gaal, whose team's unbeaten run includes eight games in the Bundesliga, one in the Cup and two in the Champions League, was furious when his side briefly lost their grip on the Wolfsburg match.
"I'm very angry because we were arrogant," he said after the match.
"We lost concentration after going 2-0 up ... it was completely unnecessary."
"I was (again) very angry at halftime," said Van Gaal. "There's no second chance in a Cup tie.
"If you lose you're out and we didn't want that. Fuerth were more aggressive than us and that can't be happening."
Club president Karl-Heinz Rummenigge praised Van Gaal's approach.
"I thought it was right and terrific," he told the club website. "After winning so many games in a row you tend to get sloppy.
"Voices were raised but the players knew at once what the coach was on about. Let's not forget we've only played four games since the winter break and the intense phase is only just upon us.
"If we make the kind of mistakes we made on Saturday, there'll be a rude awakening in the Champions League. Louis van Gaal thought 'nip it in the bud'. That was Van Gaal the psychologist," added Rummenigge.
