At the command line run:
top , then press 1 to see the cpu usage per processor (first column)
Alternatively you can install htop, which is a nicer version (imo). To do that you would need :
sudo apt-get install htop
htop
All of the coyote_miner processes should be at the top, with the first line being the total of all and the rest being the individual threads. I like to hit F5 for the tree view.
Now unless you changed the number of threads it uses, it should be using all of them. Though as mentioned above it seems to need more than one instance per 8 threads..