The number of discrete gpu's you can have is a function of the motherboard; the cpu has nothing to do with it.
If friend is talking about the number of compute elements in the integrated graphics included with the cpu, that is another question.
Generally, the latest generation of processors will have mote capable graphics capability which is partially because of more included graphics processing elements.
If you will use a discrete graphics card for gaming the integrated capability is irrelevant.
As to performance, there is a distinction between multithreaded capability and single thread capability.
Multithread applies to apps that can use all the cores/threads you have.
For such apps, generally, I5 is stronger than i3, and i7 is...