There is no evidence for a Yiddish origin. See David L. Gold's "The etymology of English spiel and spieler and Scots English bonspiel, on pages 563-570 of his Studies in Etymology and Etiology (With Emphasis on Germanic, Jewish, Romance, and Slavic Languages). Selected and edited, with a Foreword, by Félix Rodríguez González and Antonio Lillo Buades. Alicante. Publicaciones de la Universidad de AlicanteS. Valkemirer (talk) 17:18, 28 August 2020 (UTC)
== This is in addition to my remark above.
In the first publication mentioned below, David L. Gold has withdrawn his suggestion that jitney might come from jetnée because jetnée is either (1) a reflex of jitney or (2) it (jetnée) was coined in 1915 as part of a hoax and was never in use except in a poem that the hoaxer wrote in that year.
The date of the earliest-known use of word jitney is now 8 August 1886 (as reported in Gold's article mentioned below), not the date that Stephen Goranson gave.
Gold, David L. 2018-2019. “Pursuing the origin of the American English informalism gitney ~ jitney: On the alleged Louisiana French word *jetnée and the fallacy of omne ignotum pro magnifico in etymological research.” Leuvense Bijdragen: Leuven Contributions in Linguistics and Philology. Vol. 102-103.
Here is the reference for the currently earliest-known use of jitney:
Cabriolet . 1886. “The Lima Stone Man.” Sunday Globe-Republic . Springfield, Ohio. 8 August. P. 1 .S. Valkemirer (talk) 20:03, 22 November 2020 (UTC)