Gilly’s greatest strength towards survival is her insignificance to the central plot, although she did give fans that nice little tidbit potentially regarding Jon Snow, so it’s not as though she’s completely meaningless.
Of all the people on this list, Gilly seems the most likely to survive the final stretch of Game of Thrones.
Simply put, she’s just important enough for the story to reference her and the audience to care about her, but not so important that the showrunners would go out of their way to tie up any loose ends with her character with so much to cover already.