For him, maybe, but there's absolutely no way I could pass that exam.
Literal
He [topic-ならいざ知らず], I [with-では] that exam [to-には] pass-[absolutely-できっこない].
~ならいざ知らず ('if it were him, that's another story, but...') is a set phrase that dismisses one case to focus on another. できっこない is an emphatic negative potential — 'absolutely cannot.' The sentence contrasts someone else's ability with the speaker's self-assessed impossibility. いざ知らず is literary but used in spoken Japanese for dramatic contrast.