I just tested this, casting a revenant on a character with hiding/stealth and then hiding on that character. The revenant follows and tries to reveal the character. Since the revenant only tries to reveal the character within 3 tiles, it's possible to kite the revenant around and never be revealed, but it does try to reveal stealthers!
Note that a revenant's ability to detect is also based on the Spirit Speak skill of the caster. At 120 Spirit Speak, it only gets 90 Detect Hidden, which usually doesn't work on a character with 100 Hiding (the chance is only about 15%). I will see about verifying the chance on OSI.
Edit: The low chance appears to be OSI accurate.