Probably bots. Whenever you see a + sign next to a number, it means all those players are actually bots. There are very few actual people playing the game these days; UT3 is almost dead. There will be maybe 100-150 people playing the game in total on a good day, however.
Sadly people forgot about this game a week after it came out. Can't really blame them when modders were complaining the engine is to hard and with the game coming with a bug that if you played a custom map the server froze...took them about a month to fix that... Epic forgot people played UT series for the community more so than anything else. Also releasing it around crysis was dumb.