Audit report

Pervasive means the error or omission is so big that the FS are really a waste of paper. It's a matter of judgement by the audit partner and there are no hard and fast rules. Auditors are relative reluctant to produce and adverse opinion or to disclaim an opiniion. It is more useful if they can give and 'except..for' qualification because that way members get some use from the FS.

Pervasive means error has an overall impact on FS where as material error hit only the specific portion of FS...

Yes. Pervasive means that everything is undermined.