1.3 billion don't follow NBA nearly to the same level as the entire population of south east asia and a fair portion of middle East (due to migrants) that follows cricket (which is more than the population of China). Even the poorest follow Cricket in South asia...that's how big of a sport it is there.NBA is very popular in China which has a larger population than India. Also cricket is no where close to soccer which is also the most popular sport among the 1.3 billion in China.
Then you add in other countries like Australia, New Zealand, South Africa, England, The Caribbeans where it is highly popular. Followed by the associate countries where it is atleast somewhat popular.