Yes it does WHILE IT IS OUT. I had my automaton out fighting in campaign with it the other day and after about an hour or so, he hardly ever got hit by the orcs, but was able to deal a bit out himself. But after I 'Deactivate/Activate'-ed him again, he started to get hit again.
So I assume it's not permanent, but only while it is out fighting and hasn't been 'turned off'. I had zoned (using the teleport from the NPC back to town) and came back and he was still avoiding fine. But as soon as I had to recall him (I had gained a level and needed to reset his stats...), his avoiding must have been reset, since he was then taking hits again. Hope this helps.