Firmino netted two winners in as many games for the European champions at the tournament, which Liverpool won for the first time thanks to Saturday's 1-0 victory.
The 28-year-old is often questioned due to his lack of goals – he has six this season – despite his vital contributions, but Brazil team-mate Alisson talked up his importance.
"We know and he knows how important he is for the team. And we value him a lot. I think he is one of the most important players for us," the goalkeeper said.
"He doesn't just score, but he assists too. He makes the team play from behind, he helps us a lot and makes a difference.
"We are really happy and I am really happy that he could score, it's important for a striker to score and I'm really happy for everybody and this title."
Liverpool needed extra time to get past Flamengo, with Firmino netting the only goal in the 99th minute.
Divock Origi, who replaced Firmino during extra time, also hailed his fellow forward.
"'Bobby' is an amazing player. He showed it again, the finishing for me was top class and it helped us win the game," he said.
"I told him after the game I'm very happy for him."
Liverpool, who are 10 points clear and have a game in hand in the Premier League, visit second-placed Leicester City on Thursday.