I'm going to suggest something rather bizarre. If you want to increase the numbers of elephants in the world, encourage people to start eating them.
What happens to animals that people eat? They are bred in captivity. You will not find pigs, cows, chickens, turkeys, etc. on any endangered species lists because there are millions if not billions of some of them, because people like to eat them.
So if we start encouraging people to eat Elephant burgers and elephant steaks, you'll see people start raising them and the numbers skyrocket! Then you won't have to worry about poaching.