Ehm. It's public. Anyone can verify this by looking at the transaction volume in the various currencies, multiply and add.
It's actually not that simple, as traders with higher 30-day volumes are given discounts on the trading fees. Even a relatively small trader could get down to rates of 0.50% and larger traders, who probably make up a significant percentage of the volume, could get as low as 0.30% without too much trouble.
https://www.mtgox.com/fee-scheduleI would guess that their revenue is more in the $6-7 million range, and is potentially lower than that, depending on what percentage of the total trade volume is accounted for by the largest traders.
Evidently quite a bit. And i'm guessing they've negotiated rates far lower than whats on the schedule due to the risk of keeping funds at Gox.
https://bitcointalk.org/index.php?topic=278643.0Agreed on both points.
Doing an analysis like klao's, one could determine an upper bound for their revenue. Even assuming that every single trade is by a new user, those 1000 BTC trades would already put you in the 0.46% category and make a fairly large dent in their revenues.
Gox originally posted that fee schedule back in Dec 2011, so the values of those BTC figures has gone up ~40x since then. I doubt that most large traders would have been willing to trade on the same fee schedule even last year when the fiat values were in the 3-4x range, let alone now.
Anyway, I'm glad I found this thread before I started attempting arbitrage myself. But if I can find a friend with a bank account in Japan...