Uber has 40m monthly active riders, who spend an average of $50 per month each

"Travis Kalanick says his drivers’ license is expired — though, of course he has to say that. But in Kalanick’s future, with a fleet of driverless Ubers shuttling people around, it might be that everyone’s drivers’ licenses will expire.
His company, Uber, could essentially be a replacement for owning a car for Kalanick, and also for the 40 million monthly active riders the company has. Kalanick revealed that number on stage at the Vanity Fair New Establishment Summit this year in San Francisco. Kalanick also said that drivers made somewhere between $1.5 billion and $2 billion last month. Those monthly active riders pay around $50 per month, he said."

Source:  Techcrunch, 19th October 2016