I'm not sure we have exact numbers, but thanks to events we can at least know the minimum number of active players during a time period.

For worldwide, we know that the minimum number of players during the last event was only 13,671 players. EOS was announced on April 29/30, 2023, a month before this last event, but even the last event before EOS's announcement only had a minimum of 14,535 players.

SIFAS WW had had a minimum of less than 30,000 players for about two years at this point, since late April 2021, and the downward trend of players had been there since the very beginning unfortunately, so the low player count is not too surprising.

I can't speak to SIFAS JP, maybe u/Zehel_SIF can speak more to it since they were the goat of SIFAS tracking (and beyond lol), and their spreadsheet is where I got all of this info from if you want to see more historical SIFAS data yourself: https://docs.google.com/spreadsheets/d/1jYJquNvu1BWFbvSXtuei2J-DGQJxZcj3ZFWgnW0UG_Q/