The authors agree in noting a possible Germanic origin for this surname. E. Rossoni proposes that it could derive from the medieval Germanic name Gaidus, documented in the Lombard period in the form "Rotcausus et Gaidus ducibus cum nobilis Foroiulanorum consilio inito", or from the place name Gaeta and similar places. Rossoni also mentions an alternative hypothesis based on the Arabic gaydah ("forest"), although he considers it less probable.

V. Blunda specifies the Germanic etymon by identifying it with the root wahta ("guard, night watch, sentinel"), which gave the Old Spanish guaita with the sense of watchman and shares its origin with the English watch and the German wachen. Blunda explicitly rules out the association with the musical instrument, which he considers a false etymology, since the word has an independent lexical origin.

Rossoni also gathers the opinion of G. Rohlfs, according to which the variants Gàita and Gàito are surnames of Basilicata and of the Salentine area —that is, the southernmost zone of the region of Puglia, in the south of Italy— that come from the Spanish gaita, referring to the musical instrument. As for the geographical distribution, Gaita is peculiar to the Avellino area; Gaiti presents presence in the Bergamo area, along the river Serio, and also in the Parma area; Gaito is concentrated in the Naples area and the north of the Salerno area. Blunda places the surname in Sicily.