A new report this week from Citi analyst Mark Mahaney forecasted that YouTube revenue could exceed $1.3 billion in 2011 and rise to almost $1.7 billion in 2012 (see below). Mahaney's conclusion is based on YouTube driving higher video views and an improved ability to monetize these views with advertising. Google has of course been famously tight-lipped about YouTube's financial condition, other than to issue increasingly optimistic statements in its quarterly earnings calls.
To put Mahaney's forecast into context, a December 2010 online video advertising forecast from eMarketer pegged the whole online video industry's ad revenue at $1.97 billion in 2011, meaning YouTube alone could account for approximately 65% of the entire industry's revenue (granted it's dicey to mesh numbers from two different forecasts).