Matthäus also warned that PSG will not be able to sustain the same intensity at the Allianz Arena.
Tuesday's match at the Parc des Princes was the highest-scoring semi-final in Champions League history. Khvicha Kvaratskhelia scored twice and Ousmane Dembélé netted a brace as PSG led 5-2 before Bayern Munich fought back through Dayot Upamecano and Luis Díaz. Harry Kane and Michael Olise had scored for the visitors in the first half.
Writing in Kicker magazine after the first leg, Matthäus was unequivocal about the outcome of the second.
"I give it as a given that Bayern will reach the final. On Tuesday they were already the better team."
He pointed to Bayern's physical superiority in Paris as the decisive factor for the return leg.
"PSG won't be able to maintain that pace in the Allianz Arena for 90 — or perhaps even 120 — minutes. That could be Bayern's greatest asset."
He also noted a defensive vulnerability in the PSG backline that he expects Bayern to exploit, adding that the French side were running on fumes by the final whistle in Paris.
Matthäus reserved special praise for Díaz and Olise, drawing a historical comparison that will resonate with Bayern supporters.
"Since Luis Díaz and Michael Olise have established themselves as world-class players, you can already compare them — after their brief spell in Munich — with Arjen Robben and Franck Ribéry. That is quite an honour."
Toni Kroos, speaking separately on Sky, called the tie a 50-50 contest between the two best teams in Europe. The second leg takes place at the Allianz Arena next Wednesday.