I'm guessing you're not aware that top secret clearances more often than not require "code words" and you are read in aka given access to said code words on a strictly need to know basis. Some code words themselves are classified. Having a too secret clearance does by know possible way grant you access to everything like say the US nuclear defense details.

>Because if they are "heavily" spying on the U.S., they already knew all what Snowden had, and more.

We don't know this, and how would the Chinese know specifically what Snowden has? Do you have anything to suggest that they did?

>How many gov employees + contractors have top security clearances in the US? That's how.

This doesn't say much. Just because you have a clearance doesn't mean you have access to classified documents. In the miltary, for example, almost all aircraft maintainers have a secret clearance and they just fix tires.