What are the requirements for an undergraduate student to enter Harvard University?

Harvard is "blind" to financial needs on applications. And generally, after acceptance if financial help is needed it can be worked out.

Acceptance requires overall exceptional academic achievements combined with a showing of character, ability and desire that would separate you from other contenders. How much one will be weighed over the other may vary, as someone shown with unbelievably exceptional ability in a field, and perhaps not the interest and academeics in another, may still be accepted.

Other evidence of ability, dedication, essays, interviews, recommendations, etc., all will be required.