Facebook's revenue from China-based advertisers reached an estimated $5B in 2018, or about 10% of its total sales, helped by its local advertising resellers (New York Times)

New York Times:
Facebook's revenue from China-based advertisers reached an estimated $5B in 2018, or about 10% of its total sales, helped by its local advertising resellers  —  SHENZHEN — Facebook's apps and websites have been blocked in China for years.  The company has no office in the country that supports its social networking services.

from Techmeme http://bit.ly/2Gdju1H