Facebook says it now has 1.11 billion people using the site each month, slightly more than the 1.06 billion reported three months earlier. It represents a 23 percent growth from a year earlier in 2013 .Facebook also says it had 665 million active users each day on average in March, up 26 percent from a year earlier, and 751 million using Facebook from a mobile device each month, up 54 percent.
The above chart from Statistica shows how Facebooks advertising revenue has been projected by emarketer. From $4.3billion in 2012, Facebook's Ad revenue is set to grow by 20% in 2013 which is expected to reach $10billion by 2016 and from there on to $12.6billion by 2018. This means that Facebook Revenue is set to grow by 400% in the next 5 years.
This means that in 2012, 750million Facebook users contributed to $4.3billion of Facebook Revenues . leaving aside the PAT and other expenses .. Each facebook user contributes approx $5 of Revenue