Wait okay I think I mixed them up.
Rundown of the Kane fortune.
Roderick Kane sold most of Kane industry.
Nathan inherited what seems to be most of the fortune. He's very rich when he married Kathy, then she inherited his fortune on top of her own, and then she faked her death and I don't know where the fortune went. She's still a rich secret agent secretly alive, I just don't know... anyway!
Jacob and Gabi are both military and moved around, I don't get the impression that they care about business...
Philip wants the Wayne fortune as well and heads the Wayne Enterprises until Bruce returned, merging it with his company. He was blackmailed to joining Red Hood Gang and then killed. (I don't know if the merging causes Bruce to be the head of both Kane and Wayne industries)
Then there's Bette's unseen father.
Catherine Hamilton is an heiress Pre-Flashpoint, New 52 onwards I don't know, but usually they don't change things unless it's necessary for plot, like the whole Philip Kane thing, and I don't think changing Catherine's inheritance is their priority.
So however much left of the Kane fortune and industry that didn't go to Kathy (and then she faked her death) is divided between Jacob and Bette's father (if he's alive), then Kate's fortune is what she got from Jacob plus Catherine, plus her job
By the way I read up the New 52 Batwoman scene again, and got distracted with Kate refusing to take orders from Batman because of the daddy issues that might imply. Lol. This was before the retcon that they're family.
Anyway, the scene. I read it as her making an excuse for Maggie too, although she could derive it from her real job.