Does That Pitch assign IPI Numbers?

That Pitch does not assign IPI numbers. An IPI number (previously referred to as a CAE number) is an international identification number assigned to songwriters and publishers by their Performing Rights Organization to uniquely identify them as rights holders. 

Your IPI number is available in the repertories of ASCAP, BMI, SESAC, and any other PRO's. They can be found by searching for your name in their respective repertory searches on their websites. 

tl;dr: No, ask your PRO directly 🙂