In an article I found it said the meaning of it is "I will drink tea." But in another article it showed the meaning to be "(Someone is) drinking tea." So can it be used to say "He/she is drinking tea" and "He/she will drink tea"?
can mean two different things.
1) "(Someone) drinks tea (customarily)."
2) "(Someone) will/is going to drink tea (now or in the near future)."
However, to speak strictly on the native level, the sentence cannot mean:
"(Someone) is drinking tea (at the moment)" as in the present progress.
That would be:
In Japanese-as-a-foreign language, however, I am aware that they simplify things a little for the beginning students. One such example would be to teach that 「お茶を飲みます。」 can mean "(Someone) is drinking tea."
This type of simplification takes place in teaching foreign languages in general and not just in Japanese. So, I could not say that you should, as a beginner, speak and write just like a native speaker does.
The sentence literally just says "drink tea". It does not say who is doing it.
[彼・彼女・私は]お茶を飲みます。 [He/she/I] drink(s) tea.
It is important to remember that the Japanese present tense can refer to an event that is happening now or a repeated action or even something that will happen in the future, so it can be used to say either "drinks" or "will drink".