The average home attendance for gameweek 17 of 2017 in the Airtricity League premier division (which is the most recent I found with a 5 second google) was 2,325 (not the highest average of the season) 6 x 2,325 is 13,950. Connacht don’t even have a stadium that holds that.
Leinster, and Ulster had an average of less than 16,000 last year & Munster an average of less than 13,000.
So without taking into account the first division your statement is false for both Munster & Connacht.
That’s before we factor in the NI soccerball league