This sentence can mean either the statement or the question depending orally on intonation and in the written form on the addition or otherwise of the question mark.
In the full written form there is a difference between the sentences:-
Rydych chi'n yfed cwrw = You drink beer
Ydych chi'n yfed cwrw? = Do you drink beer?
But in the oral form the contracted 'dych' is used for both.