The English outfit failed to find their rhythm in a 3-1 defeat at the Parc des Princes last week and Mourinho labelled Javier Pastore's late goal "ridiculous" while bemoaning his lack of "real strikers".
"I believe (that Chelsea will progress to the semi-finals) and my players believe, and that's the most important thing," Mourinho said.
"If you ask me if we are going to win tomorrow, I say yes. I think we are going to win. In the end of the two legs I think we are going to score more goals than them."
Despite Mourinho's assurances, Chelsea's strikers have failed to impress this season. Samuel Eto'o, who has scored all his 11 goals for Chelsea at Stamford Bridge, is unlikely to play a full part on Tuesday as he has a hamstring injury.
A lack of faith in Fernando Torres and Demba Ba meant that Mourinho deployed German winger Andre Schuerrle as the lone front man in Paris.
PSG have their own problems up front, with talismanic striker Zlatan Ibrahimovic missing with a thigh injury, but Mourinho said a club with their riches should be able to cope.
"Eto'o didn't play the first game and I'm not sure he will play the second game," he continued. "Ramires is suspended, (Nemanja) Matic and (Mohamed) Salah cannot play in the Champions League and we are not crying.
"The fact that a multi-millionaire club that buys players and players doesn't play one important player like Ibrahimovic, I don't think it is a problem."
PSG coach Laurent Blanc has promised that his team will attack Chelsea from the first whistle, but Mourinho did not seem fazed by his opposite number's aggressive tactics.
"They can say they come to attack, but maybe they don't cross the midfield line," he added. "Maybe they say they come to defend and they find spaces and they score goals, you don't know.
"The only thing that I know is that if we don't score a minimum of two goals we have no chance."
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