I guess he isn't talking about speed (bandwidth), but data rate (total data sent during month).
If you go to create new server ingame, you can play with different settings and see how nuch upload is required. I got that 47 connection, 32 cars, and 6 packet per second is something like 800 KB/s. By simple maths you can calculate maximum data during month (it goes up like 2 TBs
), but I guess that your server won't be full all time.... Its hard to say without having some experience in hosting and reviewing your data rate