The first step is to get them to eat frozen food like frozen blood worms, fish fillet pieces, shrimp. Once the pike knows that you provide food, the next step is to feed soft pellets. You can soften the pellets with the juices of the frozen food to get them used to seeing the pellets as food.
Pellet training is hard if there is no competition in the tank to tell them the pellets are food.
Pikes can easily go 3 weeks without eating.
It's best to leave the room sometimes, and come back later to see if the food is gone. Some fish won't eat in front of you at first.