If you want to make a tea, simply make a tea!
I've only used caapi bark for tea, in that case I use maybe a liter on 20 gram, boil it for 30 minutes and drink. The same bark can be reused at least once, with a longer boiling time the third time. With the case of leaves (which also have a different alkaloid content than bark), I would think that less boiling time is needed. When you're not performing a real extraction but rather making a tea, I wouldn't worry too much about the exact amount of water and the exact boiling time.