The Germany international has been plagued by injury this season but has been in fine form since returning to the pitch two weeks ago.
Reus has found the net in each of his three appearances since his latest comeback and Tuchel hopes for more of the same against Bayern.
"Reus has now scored twice in the league since his return and he also scored against Monaco," Tuchel stated at a news conference.
"He is scoring crucial goals and is showing how much we were missing when he was unavailable.
"He gained a lot of confidence when he was recovering from injury during pre-season. His character has grown.
"I think Marco is ready to achieve great things."
Dortmund were beaten 4-1 at the Allianz Arena in the Bundesliga earlier this month, but Tuchel is confident they will do better this time around.
"Two weeks ago we were without a chance, but now we feel ready for a big performance," he added.
"We had six players who never played in Munich before in the last game.
"It is a pressure that you cannot feel in a video session.
"It is kind of like going down a black slope. You are likely to do better the second time."