Try giving him a bottle of water at night instead of milk -- this is especially pertinent if he has teeth, as a child should not be eating
at night (except
breast milk) because of the risk of tooth decay. (
Breast milk does not cause it, but formula does, and juice is way over the top in terms of sugar.) If you can get him to take a bottle of water, that will give him a little less reward for waking up.
But really, 8 months does not seem very late for him to be waking in the night.