I've been pondering about a word that Mexican spanish uses (as a colloquial). The word is -ey- which translate to yes.

{{It's primarily used In Mexico, California and elsewhere.}}

I would like to think that -ey- is somehow connected to etiam or aio. Then again, it could be a English influence? Who knows, but what I do know it's definitely used and said....and it's remarkably similar and looks evolved from etiam or aio. That is, if in fact it derives from either one of the two.

my theory;
Etiam=ecia=eia=ei=ey*
Aio=eio=ei=ey*

Classical Latin: Etiam, Ita, Sic, Aio
Spanish: Sí
Mexican-spanish: Sí and Ey
Italian: Sì
English: Yes

I've noticed other colloquials of Mexican-spanish, observe:

Colloquial Mexican-spanish:
Noliase (=It doesn't matter or it's of no importance)
Semiase (=I believe/think/guess so)
Tons (=then, then, at that time, and so; well then.)
Ey (=yes or yeah)

-

Standard Spanish:
No importa
Yo creo/pienso/imagino/supongo (que sí)
Entonces


---->

Could noliase be derived from "nolens or nolui " {unwilling} or something else?

Nolens=nolen=nolie/nolia=noliase, (example, "tener/tenerse")
Nolui=noli/nolia=noliase (=nolia + se)
Tunc=tonc=tons?
Etiam=ecia=eia=ei/ey
Aio=eio=ei=ey

*This is what makes languages interesting to study and learn them.*
More than colloquial is a deformation of the language.

noliase comes from no le hace

semiase comes from se me hace

tons comes from entonces

¡ei! means ¡sí! and ¡n,n! means ¡no!
Sanz, could it be possible that "ei" is related to Classical-latin's etiam or aio?
ei- does look* (being the keyword) evolved/derived from Classical-latin. I find it strange, that -Mexican-spanish tries (consiously or unconsiously) to mimic it's predecessor (i.e Latin) and how words are closer to it's predecessor. Another example:

Well (English)
Poi (Italian)
Pues/Pos (Mexican-spanish)
Pues (Standard-spanish)
Post (Vulgar latin)
Post (Classical-latin, which literally meant to be "after or in pursuit something or someone.")

Nowadays, standard-spanish uses "pos" as Classical-latin did.
I'm not sure about the true of your theory, however I don't think is related with "ey" as "sí". Other ways to say "yes":

"i" where "s" is omitted.

"mju" that's a difficult sound to represent with letters and "j" is softer than usually.

"ajá"