The Sweden captain has scored more than a third of PSG's goals in Ligue 1 this season, helping his side pull 10 points clear of second-placed Monaco with five games to play.
However, Ibrahimovic has not featured for the French champions since their UEFA Champions League quarter-final first-leg win over Chelsea due to hamstring trouble.
In his absence, PSG have lost their last two games without scoring, exiting Europe's premier club competition in the process to leave Blanc under pressure.
Ahead of PSG's Coupe de la Ligue final clash with Lyon on Saturday, the former France coach conceded his star striker's injury had played havoc with his team selections.
He said: "When you lose Ibra, a player so important to your style, then that changes everything.
"You can compensate for his loss but the style changes because Edinson (Cavani)'s style is not exactly the same as Ibra's. We haven't scored in the last two games and we need to get our effectiveness in front of goal back.
"We need players who pass the ball well as (Ezequiel) Lavezzi, Cavani and Lucas (Moura) like to get into space and they need good service."
PSG suffered a 1-0 defeat to Lyon just last week, with club president Nasser Al-Khelaifi publicly backing Blanc in the aftermath.
Blanc is accepting of the intense scrutiny he and his team have faced, and is confident he can channel it into a positive performance at the Stade de France.
He added: "We're used to the pressure being on us and that doesn't change.
"Both teams want to win the final. I have no doubts concerning my team but I know they (Lyon) are playing to win too.
"If you insist then, OK, I'll accept the pressure is more on us because you think PSG should win every game.
"It's normal that people are demanding of PSG. Wait for tomorrow's result before assessing the season. There are two possibilities so why are the questions about a potential negative result?
"The positive result is the alternative. We want to win and we're preparing to win and there are two possible results."
