Questions & Answers about Bana bu kadar çay yetiyor.
It’s the present continuous of the verb yetmek “to be enough, to suffice.”
- Stem: yet-
- Suffix: -(i)yor (present continuous)
- Person/number: 3rd singular (because the subject is “this much tea”)
So yetiyor = “is (currently) enough / suffices.”
Certain Turkish verbs that express needs, sufficiency, suitability, or effect take the experiencer in the dative. Yetmek is one of them.
- Bana bu kadar çay yetiyor = “This amount of tea suffices for me (meets my need).”
You can say Benim için bu kadar çay yeter, but that leans toward “As far as I’m concerned / In my book this much tea is enough,” i.e., an opinion/judgment. Bana is the idiomatic choice with yetmek to mark the person for whom it is enough.
Because çay is the subject, and yetmek is intransitive (it doesn’t take a direct object). Accusative marks definite direct objects of transitive verbs, so it’s not used here.
Note: çayı could appear in a different sentence as “his/her tea” (possessed form), e.g., Onun çayı yetiyor = “His/Her tea is enough.” That’s not accusative in that case, but possession.