Songwriting doesn't just refer to lyrics. We know Gaga writes her lyrics, what her producers do have a huge hand in writing are the musical elements of the track and anyone who contributes to the melody, harmonies or any part of the instrumental is also a songwriter.
lol no.
Writer means they worked on the vocal material. Producer means took care of the sound.
The definitions have not changed regardless of any possible "special" deals that Gaga may or may not have in place with the guys (which ATRLers here are wishfully dreaming & speculating about).
Aren't credits usually written in order of how much they contributed to a song.. so Guetta is like the 4th person in the list, meaning he probably had little to do with the song.