Just looking around a bit, some estimates peg youtube's revenues at $4 billions for 2013 and their operating income at $711 millions (18% margin?). This puts their daily revenues at ~$11 Mil and their daily income at ~$1.9 Mil. Bonus estimate: from Trefis you can get a $4.5 revenues per 1k page views, and an average of 133 page views per month per user. Using those numbers and the revenues it's easy to calculate approximately 550 Mil unique users per day.