He didn't factually give his life for Luffy however, he accepted the risk, but that's something he does daily by sticking with the SHs, although this time the risk was greater, yes. He wasn't walking the plank to be put to death like Roger however, he did well taking the gambit cause he then even survived. It's not the same situation.
Also I already mentioned how yes, he would presumptively sacrifice his life for Luffy even if it meant getting more extreme than with Kuma, but that's a different kettle of fish.
Accepting to marry Pudding would have meant saying forever goodbye to his dream to find the All Blue, he could have very well trusted his nakama more before taking such an extreme decision in order to save Zeff. That wasn't a display of massive will to me. I'm fairly confident Luffy would have trusted his nakama more than Sanji did in such instance. He trusted Ace despite his Vivre Card was bursting in order to keep his journey, he would have probably trusted his nakama in order to find a solution. Then we can agree to disagree.