I hear both may work very well to help quit smoking.
I also hear that you can get a prescription from the doctor which somehow helps tone down the craving for nicotine and actually makes it an unpleasant experience when you do smoke (don't know how it works, makes smoking taste very bitter, not sure)
There are lots of ways to do it.
Going cold turkey is only as effective as the willpower behind it.
That may be what is keeping your brother from quitting.
If he really wants to quit, he will do it when he is ready.
Change is very possible by anyone, they just need to be ready to change to implement the new pattern of behavior in their life. Until they're ready, I don't know how much you can do to change that on your end.
As far as Steve goes, he's been doing this for a very long time.
If he has implemented IM and LOA and changed the subjective reality within his perception to somehow change the behavior of his partner, it's only because he's been practicing his skill for a very long period of time.
I'm not saying it's impossible for you to be able to do this, I'm just saying that Steve has been honing his skills and training his brain to think specific ways which allows those things to manifest in his reality.
I do think it's very possible for him to do this, I'm nowhere near that skill level yet and I would say that holds true for most of us.
(that won't stop me from trying though... don't let it stop you either