Colombian frontman Falcao has netted on eight occasions already in La Liga - the same tally as Barcelona's Lionel Messi and Cristiano Ronaldo of Madrid rivals Real.
It has been widely reported that the 26-year-old has a release clause at Atletico of around €60m (£48.3m) and Marin said that this would solve "all" debts at the club.
However, he said the striker wouldn't be going anywhere before the end of the current campaign.
"I can say for sure, though, that he will stay with us until the end of the season. Not only will he stay, but so will all the players that the coach wants to stay," Marin told COPE Radio.
"We will fight to perform a miracle which is what we are doing with what we have available."