He kaputī māu? means: Do you want a cup of tea?
To extend a little bit on N-M possession, you can use the interrogative (question word) ‘wai’ (who) to ask:
- Mā wai te kapu tī? - Who is the cup of tea for?
- Māu te kapu tī - The cup of tea is for you (intended possession).
- Nā wai te kapu tī? - Whose cup of tea is it?
- Nāku te kapu tī - The cup of tea is mine (actual possession).
- Nāna te kapu tī i mua, nāku ināianei. - The cup of tea used to be his/hers/theirs (singular), now it’s mine.
This form of possession describes ownership. If you want to describe who is currently holding something (temporary possession) you use words describing location.
- Kei a wai te kapu tī? - Who has the cup of tea? (kinda translates literally into “Where (with who) is the cup of tea?”)
- Kei a Josh te kapu tī - Josh has the cup of tea.
- Kei ahau te kapu tī. - I have the cup of tea.