How many Cpu cores can ardour use
As many as you have – see preferences > General > DSP CPU Utilization
So if I had a 64 core cpu it would be able to use them all.
Yes Ardour is capable of that as far as I know, but whether your session will be able to actually utilize that is something else. It’s not quite as simple
If it’s used for film and other large projects then ya it would be nice to have
If dealing with a large session you will likely benefit from many cores yes.
The parallelism relies on you having as many (or more) tracks as you do CPU cores. They also need to be independent (i.e. Track 1 does not feed Track 2). Under those circumstances (which are quite typical), you would get full utilization.
However, note that Ardour sessions with 100+ tracks run relatively easily on a 4 core system unless all the tracks are heavily burdened by CPU intensive DSP (like Reverbs and certain kinds of EQ), or digital synthesis.