I believe gcc is used to build the conda-distributed binaries, but only the runtime gets installed when you install the stack with conda (which is the proper behavior, IMHO – you shouldn’t need the whole toolchain to just run the code).
If you want to also build your own code using the conda-delivered gcc, run conda install gcc. Note that this is not an officially supported way to do it; very few people use it for daily development, so I’m not sure how well we’d be able to help you if you run into problems. It’s easy to try, though, so it may be worth a shot.