"Say, do you have tea?"
Translation:Скажите, у вас есть чай?
not really, there is a huge difference in the meaning of this two: "скажите, у вас чай?" can be used for example if you see a person holding a drink and want to know if its a tea, if u ask in a shop if they sell tea "есть" is very important. When you ask if they "have" or "don't have" something, using the verb is important or the people wont understand what you want
"у вас" or "у тебя" are both genitive forms from "вы" and "ты". If I'm correct, it means 'to you (polite)' or 'to you (informal)'.
Litterally 'Say + to you + has + tea ?' which of course would be more proper when turned into 'Say, do you have tea ?'. Ownership seems to use a lot of genitive forms in russian.
But then again, I'm neither Russian nor English. Sooo... Haha.