Hi

There is no definite cutoff score. There is no assurance of getting an admit from CMU even if a student has a perfect score of 340. The decision depends on a variety of factors. A GRE score above 325 would be a decent bet for CMU. However, the GRE score needs to be complemented by a balanced profile, strong letters of recommendation and a well-written SOP

A good CGPA, relevant research projects and publications, internships, previous academic records, and work experience also contributes greatly.

As far as TOEFL is concerned, even the bare minimum should be enough. It is only a proof of your knowledge  in English.

Hope this helps!