It depends greatly on the programmer, and how much time you allot them. GCC will produce vastly better code than any human programmer, given a specification in C and a time bound of 1 second. Give them ten minutes? An hour? A week?
At the extreme a sufficiently adept assembly programmer (which probably still exist) will still beat the compiler, given enough time, though that can be helped by the ability to reference the code the compiler is generating.
Not any human programmer, at least not for some tasks. The handcoded x86 SIMD code in x264 (the software video encoder used by everyone who cares about video quality per bitrate) beats the output of any compiler trying to compile the pure-C fallback function. Same for a bunch of other code you use (indirectly) like memcpy or strlen.
But the optimized handcoded routines take weeks to develop while a compiler would be done in less than a second. For almost all code, a programmer's time would be better spent on something else.
You seem to have misread what I said, and are making basically the same point I did. I said that given only a single second in which to work (and given a problem specification in the form of a correct C program) then literally any human programmer will lose out to GCC. That seems unequivocally the case, and you seem to agree.
I also said that there still exist programmers who, given enough time, can probably beat the compiler. Certainly there are tasks where this is easier, but no one is getting it done in one second.
At the extreme a sufficiently adept assembly programmer (which probably still exist) will still beat the compiler, given enough time, though that can be helped by the ability to reference the code the compiler is generating.