In compiling the kernel, the C libraries (and thus the gcc used) do not matter. Any version of Linux, with any version of the gcc C compiler should be able to compile the kernel.
The recent release of Red Hat Linux 7.0 is not recommended for compiling the Linux kernel; the main developer of Linux, Linus Torvalds, is on record as saying that Red Hat Linux 7.0 is unfit for development. This is because the released gcc is a development version — the gcc people do not recommend its use for production work. It has also been suggested that Red 7.0 came with a development version of the C libraries.