5GB = 5120MB
5120MB / 30 days = 170.7MB / day
7281KB / hour
121KB / minute
2KB / second
So I take what I said back, 24/7 you will run out since it likely uses more than 2KBps. However, I find it hard to believe you are playing literaly 24/7, you have to at least sleep which means 16/7 which would mean 3KBps average. I suppose it's possible to burn that if you have someone bringing you food/water and you play on the toilet.
But then there is the time between games as well...
Perhaps a better question is, how much do you play exactly? Do you really spend every waking hour playing video games or do you have job or go to school as well?