Four-time European champions Bayern look set to meet nine-time winners Real Madrid in a mouth-watering semi-final later this month, with the Spanish club hosting APOEL Nicosia on Wednesday and holding a 3-0 advantage from the first leg in Cyprus.
Olic, a surprise addition in the line-up ahead of Bundesliga top scorer Mario Gomez, has spent most of the season on the bench while the Germany international has been scoring at will, 23 times in the league and 11 times in the Champions League.
"I am very happy for Ivica, not only because he played well but also because he scored," Heynckes told reporters.
"He worked very hard. He is a bonus for us now. We know we play every three days and I need alternatives, players who can decide a game," said Heynckes, whose team are chasing a treble of domestic titles and the top European prize.
"To have the feeling that 'I am valuable for the team' is very important for a player," said the former Real Madrid coach.
Olic told reporters: "It is a good feeling. I am a player with a lot of experience but I was stressed before the start.
"To play in the Champions League is always something special. I am very happy to have scored and to see the team is through to the semis."
"I am really happy for Ivica. He came off the bench and straight away scored two goals. That is really important for us," said Ribery.
Olic made amends in the 37th, timing his run to connect with Alaba's low cross.
"If we had converted those early chances it could have been different," said Marseille coach Didier Deschamps, whose team are in ninth place in Ligue 1.
"We tried to get the best out of this situation. But Bayern are deservedly in the last four. The adventure was beautiful."
"Yet it was not always logical what we did on the pitch to get to the quarter-finals," he said in reference to a string of last-gasp goals
