Oh wow I didn't expect to come back to this much advice!
Have you considered Pablo Picasso? I don't reckon much to him as an artist, but definitely a source of quotable quotes.
I actually haven't looked at Picasso just because he isn't really to my taste, but I'll go check!
If they're famous enough to influence you, they must have a blog or an account on some art site where they sometimes comment. Spend some time digging through that and find a phrase that speaks to you. It doesn't have to be something deep and "quotable". Even if it's something along the lines of "a bad sketch never turns into a good final work", you can use it and say it was good advice for you. It can also be something really silly, anything will work as long as you can explain how it relates to art for you.
Edit: If they're someone you can actually talk to, like a friend or family member, just ask them "what is art?" or "why do you make art?", and there you have it, instant quote 
Oh that's a good idea, thanks.
Techincally if I were to pick someone who super influenced me it would be my grandmother, but she died when I was eight so I don't really remember anything specific she told me.
Same for Dali - if you want something completely insane
I actually like Dali so I did look at some of his quotes, and they are some of the weirdest I've come across (example: "I don't do drugs. I am drugs." don't think the school would appreciate that too much :'D).
You don't happen to be a comic or cartoons fan? The artist is not always, but often, the one to write the scripts. You could pluck something from there.
Given that I am on a fan forum for a comic, yes I like comics.
But yeah, I'll try that!
I found something better. 
You got buried under all my responses but that second one is just.
Why, Plinkett, whyyyy?
