only if we say "Generația lui îsî bea cafeaua neagă" (with emphasis on neagră - beeing the important part of the sentence that carries the valuable information of the sentence)
lui is a personal pronoun (in Dative) that is also masculin and "ei" is the feminin equivalent, so yes, you can use it: Generația ei (as in her generation, not his generation). And "își" is a reflexive pronoun (also in Dative) that shows that the subject is also the owner of the object that they are talking about (cafeaua = the coffee)... so "Generația ei își bea cafeaua neagră" could be translated as "Her generation drinks its' coffee black"
and if i i used sieși then i would be stressing the owner rather than the coffee?
yes it would stress too much to whom you are doing the action (to yourself) rather than the action itself
In the english context, 'drink' should be a valid answer here. "His generation" implies multiple people, so the plural form may be used. "[The people of] his generation drink..." etc.
So I looked this up. In BRITISH English a collective noun is more often treated as a plural for verb conjugation so
His generation DRINK black coffee.
should also be accepted. It is correct British English. While used less often in the US it is apparently not an absolute exclusion there either.
I have reported but post this to explain.