He was struggling with a very large conger, and holding fast with one hand to the side of the vessel, in order to seize with the other the gaping jowl of his antagonist, when the master said to him, Take care they don't see you from Belle-Isle.
In Naruto each base-element is stronger and weaker than one element:-. Fire: strong against Wind, weak against Water. Wind: strong against Lightning, weak against Fire. Lightning: strong against Earth, weak against Wind. Earth: strong against Water, weak against Lightning.
In my opinion I feel that Natsu could beat Naruto but that being said at this point in the manga of One Piece how strong luffy is now with his gear 4th could change with him truly awakening his devil fruit power. So I think that it would be a really close fight between Natsu and Luffy.