Yoshikawa (Yamada's author) had been on Mashima's team for a long time before getting serialized. And yes, that means she's been on his team since Rave. And you have to wonder... Considering how he wrote HaruxElie, (and MusicaXReina) along with NaLu and the rest of the ships in FT, if Yoshikawa was a major influence in the shipping aspect of the stories.
Yoshikawa specializes in Romcoms, so you wonder who influenced whom when it comes to writing romance.
Well considering on how open ended Yoshikawa's last work ended (Yankee-kun to Megame-chan), and her romantic preferences, I'm not so sure. Mashima doesn't have love triangles, he makes his pairings obvious, where with Yoshikawa's work the MC seem to have more than one female interested in him, and we can never be sure if the MC will end up with the girl he likes at the end.
Her preference from the two manga's suggests she likes complete opposites, very Shoujo like, in the sense it's usually a percieved dumb bad boy and a smart book nerd, (Though in Yankee-kun it turns out to be the other way round.). Also it's the guy who realises their feelings first and pursue the girl the like, in Mashima's work the Male charactors feelings are usually not made as clear.
The humour on the other hand I can see her influencing, I can't remember there being much comedic fighting between the cast in Rave, but in FT they all seem to be at it that's something that has been in both Yoshikawa's work.