How many AOA sensors does the 737 MAX have?
The Boeing 737 MAX has 2 AoA sensors.

However, MCAS only takes input from 1 AoA sensor at a time.



Sources:

The black box flight recorder data for Lion Air JT610 shows the data from 2 AoA sensors, labeled "Left" and "Right".

Also, if you look at the nose of the 737 MAX, you will see a left and right AoA vane. (The sensors with the red tags are pitot tubes).

"[Boeing] said it will change the MCAS software to give the system input from more than one AOA sensor."