Almost all PC-targeting distros are going to have a way to install GCC, as you can't compile the Linux kernel without it. But it won't always be installed by default, and even if it is, can be removed by the admin.
Example: I don't think it's installed by default on Debian. (Though the installer gives you a wide selection of which packages to install, so there are many default package sets.)
You also surely won't find it installed (or possibly even available) on embedded Linux distros as GCC is fairly big, in both storage and RAM requirements to run. Instead, it's installed on a non-embedded machine and everything is cross-compiled.