One early problem with Pascal was fragmentation: while there were various decent, proprietary, dialects that let you actually write code that did stuff, *standard* Pascal was as much use as a chocolate teapot. Standard Pascal had lousy I/o and minimal libraries. the standard didn't even specify how to open a file, whereas C always had a decent subset of the Unix API as part of the de-facto K&R standard.
Had Pascal come a few years later when the IBM PC had crushed all before it, then something like Turbo Pascal might have been far more successful. However, back when there was more than one type of PC to worry about, C's huge standard library, and it's preprocessor for fixing minor dialect issues made it unbeatable for writing portable code.