The Firhill chairman this week rewarded boss Jackie McNamara with a new contract following the club's stunning start to the season.
Thistle have a two-point lead at the top of the Irn-Bru First Division and have booked a place in their first cup final for 41-years.
The Jags attracted a bumper attendance of 5,268 for their top-of-the-table clash with title rivals Dunfermline last month, but could only muster 2,221 as Stuart Bannigan, Steven Lawless and Steven Craig netted in the 3-2 win over Raith Rovers.
Chairman Beattie told SportTimes: "The crowd at the Dunfermline game shows how many Partick Thistle fans are out there.
"I think the ones that don't come on a regular basis are missing some good football.
"I am delighted with the crowds this season and the fans have been treated to some really good stuff.
"I know there is a marketing campaign going on for the Morton game in a bid to attract fans back to Firhill. Boxing Day is huge for us, it should be a great game.
"Since we have moved the home fans into the North Stand, there is a great atmosphere on a match day.
"The more fans that come and the more noise made the better.
"As Jackie has said, the crowd is a 12th man."