HBO Now has 800,000 subscribers in the US

"Richard Pleper, Chief Executive of HBO, has revealed that HBO NOW, the broadcaster’s OTT platform, has attracted some 800,000 paying subscribers, with Jeff Bewkes, Chairman and CEO of HBO’s parent company Time Warner, suggesting the service was a significant contributor to HBO’s 2.7 million domestic subscriber additions in 2015.
The figures were highlighted during Time Warner’s Fourth Quarter 2015 Earnings Call, during which Bewkes suggested that the combination of an even stronger original programming line-up and best selection of hit Hollywood movies and ever improving digital products would drive continued subscriber growth both at HBO NOW and with its traditional distributors."

Source:  Advanced Television, 11th February 2016