Can Darth Revan do Giga-Drain?
Is this power potentially an ability Darth Revan learned through experience on Malachor V and was lost forever after his mind was shattered?
There are two primary reasons to believe Darth Revan was proficient in this form of drain, potentiality even better then Darth Traya herself at it.
1.) Darth Revan established and taught the Sith Assassins everything: "So Revan trained elite Sith units into assassination squads, whose duty was to go out and capture enemy Jedi. I was in one of the special units trained to do this. Revan had plans for all Jedi. I think it was important that the Jedi see her side of things, the Sith teachings. Revan wanted to break them. And then have them join him." ―Atton Rand (Star Wars Knights of the Old Republic 2: The Sith Lords)
2.) Darth Traya studied the teachings of Revan found on Malachor V: "Led by a woman named Kreia, the rogue Jedi turned to the dark side teachings uncovered by Malak and Revan. Kreia took the name Darth Traya, and her followers called themselves the Sith after the long-lost species that had invaded the Republic a millennium before." ―Star Wars The Old Republic: Revan
Therefore, logic holds that since Darth Revan...
1.) experienced regularly what Darth Traya experienced on Malachor V...
2.) knew of all the knowledge Darth Traya studied when she became Sith...
3.) and personally taught "the sect of assassins" that "feed on the Force."
It can easily be assumed Darth Revan too knows of this draining ability.