Lifesteal doesn't functional at all right now due to a bug we missed when submitting the last update.
In the next server push, it will function again, but it still will not function with any of Grim Reaper Eddie's skills, because all of his skills (and his Fury) do magical damage, which won't trigger healing from Lifesteal.
Similar thing with Spell Vamp (including Grim Reaper's own Spell Vamp, where the status effect doesn't currently function, but will for magic damage attacks once the next server push goes out).