How many points if you gain 1000 battle power in upgrading a building?

Depends on the event. Hourly Challenge, CoP? In each event you can see the points you get for increasing power listed in the event description. Usually 1 building power will give you you 1000 points. 1000 = 1,000,000, points. But check the event you are doing. For CoP you also have research and tokens that give you multipliers.