Cats, like dogs, can be easily trained. It is all about finding the proper motivator for your specific cat. What can you give your cat that will reinforce that behavior, or cause that behavior to increase in frequency? Some cats may be very motivated by food while others may be more motivated by play, praise or physical attention. In my house, Cecilia is motivated by food (especially cooked chicken and hard food treats) and play while Macy is motivated more by praise and attention.
In order to determine what motivates your cat consider their personality. Is your cat extremely affectionate? If so, try reinforcing behaviors with praise and petting. Is your cat high energy? If so, try reinforcing behavior with short bouts of play. Does your cat often break into bags and steal treats? If so, try reinforcing with their favorite foods. Considering what your cat enjoys will help you understand what motivates them. Often new trainers focus too much on reinforcing behaviors with food treats, but some cats can be picky about food and many cats seem to be more motivated by activity, such as play.
In fact, while I was leading a recent kitten clicker training class we found (after a personality assessment) that 75% of the kittens were more motivated by play than by food. Next time you have issues training your kitty with treats try reinforcing with short bouts of play or petting instead.