Hi, I play Red Orchestra.
Short answer to your question is no. There are not many players left, there are 1 or 2 popular servers that are full most nights, play during the day though and you'll be playing with a lot of bots.
Theres a mod, Darkest Hour which is more popular than the base game and if you're buying RO I'd reccomend jumping straight in. Its still not that populated but there is a good dedicated community.
Saying all that, its still a much better buy than red orchestra 2!
I think its worth bothering with, I played the game in its hey day though and it was excellent "back in the day". You will have fun for sure.