Lifespan chain and gear wheels on e-bike If is possible to give an indication of the  average lifespan of the chain and gear wheels of an E-bike? 
Assuming: Cycling in all weather conditions (commute); Western European climate (10% of time rainy, snow is rare). Average monthly temperature ranges from 0 to 20. No Cycling off road. Open chain/gear (no case).
Lifespan may be in km, or in years/months assuming about 3000 km/y.
It’s impossible to give an answer because chain and sprocket wear is dependent on load as well as distance. Stronger or heavier riders apply more force. Riding lots of hills will do the same.

The best approach is to get a chain wear gauge and record how long a chain lasts for you and your riding. 

Conventional wisdom is 2 or 3 chains per cassette. Inspect the cassette when you replace the chain.