Yes, Eyer is one of the many variations included in the study.
The complete list of currently included variations is: Aaire, Aars, Aers, Ahheayrs, Ahheire, Aier, Aiere, Aiers, Air, Aire, Aires, Airs, Ares, Aries, Ayar, Ayars, Ayeres, Ayer, Ayers, Ayhaire, Ayr, Ayre, Ayres, Ayris, Eaire, Eairs, Eares, Eayer, Eayers, Eayr, Eayre, Eier, Eires, Eyer, Eyers, Eyr, Eyre, Eyres, Eyrs, Hairs, Hayers, Heires, Heirs, Layre, Le Eir, Le Eyr, LeEyre, LeHeyr, Le Heyer (those in bold are represented on WikiTree currently).
The only known variations that we have specifically not included are: Oyer, Iyer, and Hare. There are a few instances where these are comingled with the above in one or more records, but for the most part they are distinct lines or very geographically removed - such as Iyer being confused with Ayer is mostly in India.