Pretty apples to oranges here when saying something as general as '8-bit PIC' there are many architectures within that family, 4 last i knew. The low end ones are not intended for coding to with C anyway (although there are some poor compilers that try). The PIC18 series isn't bad to work with in C, I used the C18 compiler at the time and its 95% ANSI C.

I believe there is gcc support for the pic24/dsPIC (16bit) and the PIC32(32bit).

All that said last I knew Microchip still leads in 8bit mcu global market share.