Oddly enough, I would say generally yes, we do. Mach only replaces a small bit of the kernel, the rest is BSD. Source code is on GitHub and if you take a look then the usual BSD kernel files are there, and include the Berkley copyright in them, below the Apple bits. I haven't written kernel level stuff for MacOS, but I did for OpenStep, and you could simply take BSD kernel code and port it in a direct manner.
So, yes it's BSD underneath, and BSD at the command line too [though getting a little less so - vi to replaced with vim recently for example]. Sys-admining it, however, is *not* BSD-like, as someone else has commented. Don't try and configure things by editing files in /etc or you will end up very exasperated. But at a user level, if you are familiar with BSD you will find MacOS a lot more familiar than Linux is.
[ I suspect this is a moot point though, as the quantity of people in the world who are really only used to Unix and have no significant experience with Linux are pretty small in this day and age. That's me, but then I am old. And stubborn ;) ]