I would be careful with stuff like this. Sometimes stuff like this is marketing and not actually true of the system itself. I'm not saying that this is the case with this school, but I've come across it many times.
There's nothing that I've seen in Hapkido that moves like Kung Fu. To say that it resembles just means that it looks like it. Sort of like how cars from 2 different company may look the similar on the outside with body shape and design, but they aren't the same.
It may be possible that the Hapkido teacher has trained more than one system and he uses things from other systems and integrates them into Hapkido, but at that point they are creating a hybrid Hapkido system and probably should rename it it. Maybe Hapkido followed by the last name of the teacher who is integrating other stuff.
Some schools will try to say that they are "just like System A, System B, System C in an effort to attack students who have incomplete information about systems. From a website marketing perspective. This Hapkido comparison page would also get visitor searching fro BJJ, Kung Fu, Aikido, MMA schools.
https://hapkidoaustralia.com/about-hapkido/
I'm always cautious of schools who compare themselves in this manner by comparing similarities like that. Two cars may look the similar on the outside but totally different when you get on the inside and when you drive.