What do you mean by "sure"? Nothing's ever completely sure, if only because of Fate points. If you have an Item or Rote that maneuvers against someone, they get a defense roll of some sort. If you beat them they get the Aspect you wanted to give them. If you don't beat them, they're okay. So, to be entirely sure, you'd need their Defense skill +5, +2 for every applicable Aspect they had, AND +1 more for every Fate Point they might have above that Aspect total.
For more reasonable levels of surety, I suggest higher than their base defense by, say, 2 points. They'll need an Aspect use or a really good roll to resist.