How many cups is 50grams butter?

Incorrect premise.

50 grams of butter is NOT equal to any number of cups.

The conversion between grams and cups depends on the density of the substance being measured. Butter has a density of about 0.9 grams per cubic centimeter, so 50 grams of butter would be about 55.5 cubic centimeters. Since there are 240 milliliters in a cup and 1 milliliter is equal to 1 cubic centimeter, 50 grams of butter is approximately 0.23 cups.