The Dons were left red-faced after selling just 11,000 tickets from an allocation of 23,000 ahead of Sunday's 1-0 semi final win over Rangers at the national stadium.
That came after they had complained about the initial noon kick-off time for the last-four tie, which was eventually put back to 4.30pm.
But now McGinn has joined boss Derek McInnes in arguing that demand will be far higher for the showpiece on December 2.
That stance is likely to put the club on a collision course with Celtic, but ex-Parkhead winger McGinn believes it's only fair the Pittodrie side get half of the briefs.
"Yes it has to be a 50-50 split. Finals should always be half and half, no matter who the teams are," he said.
"We have shown (our fanbase) in the past. The last time we played Celtic in the Scottish Cup final in 2017 we filled half the stadium.
"And when we won the League Cup (in 2014) against Inverness we took over 40,000 to Celtic Park.
"We know that we are a big club and we know we are definitely capable of bringing 25,000 fans to the final."