Depending on which course you are applying to, there may be a subject specific score requirement. However since Harvard is an ivy league university, you can naturally assume that the requirements are high. Getting a 40+ overall out of 45 points can most definitely give you the edge.
A score of 1500 and above in the SAT could increase your chances of getting into top universities. However, it is hard to assess solely based on your SAT and GPA. You must show that you are a well-rounded student by taking part in various extracurriculars and co-curricular activities. Another major aspect in your application is the essay. If your college essays show who you are and what you are passionate about, then you might just stand a chance.
However, you should keep in mind that quality is greater than quantity as top universities are highly competitive.