French always agrees the verb with its thematic subject, not the clefted “it”.

C’est moi qui prends l’argent.

This applies even when the thematic subject (here nous) doesn’t surface:

C’est toi et moi qui prenons l’argent.

But I would say from my linguistics & editing background that this is the rule in English too.

It is I who says so. It is I who say so.

This becomes starker when the subject is plural.

It is we who says so. It is we who say so.

In any case, though, there is no ambiguity about the rule in French (cf. Académie Française).