Even though it's been a while since data miners dug up Revenant from the Apex Legends files, Respawn threw us off the trail with the Shadowfall LTM, where they had him as the criminal mastermind behind it all. However, mining never stopped.
In fact, you can expect them to be made well into January 2020, unless the dev is throwing everyone for a loop here. Again.
That said, Revenant's addition seems as certain as anything we've seen before, because not only did Respawn add the icon, which is normally confirmation of impending addition - there's a bunch of sound files to go by as well.
Revenant's passive is all about movement, as he crouch walks faster and can climb walls higher, all of which comes with a sound much like a beating heart. You can hear it at around 2:00.
Apex Legends' new character's second ability is Marked for Death, which shoots the enemy with a dagger that can be used to reveal his/her position for up to 60 seconds. Of course, the poor, marked sod is notified of being marked but can remove it if healed to full.
Then there is Silence, where Revenant throws a device that disables enemy abilities for 10 seconds. Starting at the 3-minute mark, you can actually hear the voice lines of other Apex Legends, alerting their teammates to the no-ability issue.
This is where things get a bit strange, because there are more abilities than an Apex Legends character should have.
The idea of a Death Totem, however, is interesting, as it would allow you to place a totem that respawns any dead allies with 20 health points for the duration of the totem. It also refers to Shadow Form, Revenant's ability set that was rumoured a while ago, which to me smells of another Respawn trick to throw everyone off the trail, an LTM or both.
Prominent Apex Legends data miner iLootGames found some additional abilities as well, like the poison bomb. However, he thinks those will be removed, as they're pretty close to stepping over Caustic's set of abilities.