Yeah, the LD50 of water is maybe ~6-7 L [0]. If ~100 mL / cup, you're approaching that volume of coffee with 50 cups. The small amount of sodium in coffee may help. (Ignoring how fast these are being consumed.)
I'm sure the Voltaire thing is just "the dude drank a lot of coffee."
I'm sure the Voltaire thing is just "the dude drank a lot of coffee."
[0] http://www.sciencelab.com/msds.php?msdsId=9927321