When you brew tea, flavour and natural compounds pass from the leaves into the water. How much of them ends up in your cup depends mainly on temperature and steeping time. Olive leaves are firm and leathery. They need a little longer than fine tea leaves.
For our Ölich Olive Leaf Tea we recommend 2 to 3 g per cup, that is 1 to 1½ teaspoons. Pour over water at about 90 °C and steep for 7 to 8 minutes. If you prefer it milder, use a few fewer leaves or shorten the steeping time.