No sé si tú les gustas a los otros, pero a mí, sí.
"les" because of "otros", and "sí" because you mean "yes", not "if".
EDIT: "los" added after being brought to my attention by the comment below.
Almost :P "No sé si tú les gustas a los otros, pero a mí, sí."
Is this sentence an example of slang conjugation? I think I've seen verb forms like these on the internet before... In academic Spanish, if you are trying to say "I don't know if others like you, but I do," I believe that "No sé si a otros les gustas tú, pero a mí sí" is more precise. However, I might need some clarification. Sorry for the bother!
I'm afraid I'm not sure what you mean by slang conjugation in my sentence. The only difference between my suggested sentence and yours is sentence order, both of which are valid :-)
Mine: No sé si tú les gustas a los otros, pero a mí, sí.
Yours: No sé si a los otros les gustas tú, pero a mí, sí.
One could, in addition, even add "me gustas (tú)" to the final part of the sentence to be even more explicit. So, the final, very clear resultant sentence would be: "No sé si a los otros les gustas (tú), pero a mí, sí me gustas (tú)."
Soy hablante nativo de español y se puede entender de esa manera. Desde mi punto de vista "les gustas" suena mal pero quizás estoy equivocado, aquí en Venezuela siempre lo he escuchado de esa forma.
Remember that this also works with other verbs, such as "encantar":
[A mí]-[me][encantan][las películas] = I love movies
To add to this, here are additional common verbs that use this structure:
faltar (to lack): Le faltan dos dólares. He is two dollars short.
doler (to ache/to hurt): Me duele la cabeza. My head aches.
interesar (to interest): A ella le interesan los deportes. She is interested in sports.
Also, in Spain the verb "molar" is quite common. It can be used just like "gustar" with a similar meaning (although it has a lot of other meanings, for example, "Quiero molar" = "I want to be cool").
Me mola la foto = I like the photo
La foto mola = The photo is cool
The adjective is "molón," so you could say, "Quiero ser molón" = "I want to be cool." Take a look at the SpanishDict page for "molar" here.