groups are limited to 20,000 players and while we have two groups one of 20,000 and the other being 17,000+ we have been forced to open a third group in prep for more players wanting a pve game.
But in regards to numbers I can say that with information from frontier at least 17,000 form one group do log into the group on a regular basis.
while some may say that they have not seen another commander while in Mobius,the same argument goes for open when people say that they don't come across anyone for ages and keeping in mind open has a few hundred thousand players. the weekends are the busiest times and while my friend list is only around 1000 at any given time 200 are logged in, while this is not a true indication of how many players are playing online I will say that I constantly come across players that are not on my friend list and to this day continue to add players when I come across.
the Mobius community is very active but frontier have been very tight lipped as to how many actually play within our private groups, only they can give the true numbers as to how many desire a pve game.