So let's say you do 30 matches a day(30x5 minutes average match time is roughly 150 minutes, IE 2 and a half hours.) with an average XP of 300. I average about 200 on a loss, 500 on win at tier 5 with my Mat-BP and T-25. Splitting the difference 300x30=3000+-1000 in case he plays an extra 10 matches
So to make it to the FV415b, a tier ten brit tank destroyer, and load gold, you'd need, hang on let me math, from where I am at the alecto, because you can generally factor it to about 6k xp to get to a tier 4. 1100 for the tracks, 13.5k for the AT2, 3.7k for the gun 29k for the at8, 4k, and 14.5k for the guns, 56k for the AT7, 15k for the next gun, 92k for the AT 15, 16.5k for the next gun, 161k for the Tort, 45k for a gun, 60k for a gun, 235k for the FV215B 183. So to calculate using the most xp per day I've ever gotten, 16k and that was playing 8 hours that day. 697,600, dividing that by 16,000, 43 days, assuming he managed 16 thousand experience a day, that's over 80 matches.
EDIT:Oh and as far as gold goes, dividing the number by 25, gets you 27904, or roughly 125 dollars.