How many magicians quit after the 7-year time skip? After the time skip following the Tenrou Island arc, a lot of Fairy Tail members quit.
So, my question is: how many members did Fairy Tail have before the time skip, and how many do they have after the time skip? How many of them quit?
Yes, after the "Tenrou" arc, most of the Fairy Tail members quit the guild, but all the members who had screen time are still in Fairy Tail .

Most of the important characters, or characters who had major or average screen time and were at "Tenrou" island (Natsu, Ersa, Lucy, Gajil, etc.), and even the most minor characters who had less screen time (like Waren, Romeo, Romeo's father, etc.) are still in Fairy Tail.
Even if some characters are missing (I personally didn't notice any), all the important ones are still in Fairy Tail even after "Tenrou" arc. On the plus side, we even get a new character - Kinana.

My answer is based on only the anime, not the manga.