That isn't 8 hours, that is 8 days, 1 hour, 33 minutes and 48 seconds of dbl xp time.

So in short, yes, he is cheating.

I'll message ban candy his gt, and he'll be banned/reset by the end of the day.

Even if he used all his prestige tokens on double xp and his clan was level 50 (which is unlikely), that wouldn't add up to 8 days of double xp.  You realize 8 days is 192 hours right?  There's no possible way.  The most you could get from doritos, mt. dew, etc was 24 hours.  The most prestige tokens one could have (4 from previous games + 15/16 from this game if you're the highest rank) that would only be like 64 possible hours you could have legit.  The clan xp would have to account for like 130 hours of double xp, and that's not possible.  So he's a cheater

W7PSK, PM me his GT and I will see that BC takes care of him.