Is a khajiit Mage viable ?

I want to be a khajiit for next race and a Mage for next playthrough will it be ok or should pick a high elf or Breton for a Mage???

It won't be the best Mage to start with, but they made the games so any race can be any class with enough time. So yes, you can be a Khajit mage, just expect it to be a little harder in the beginning of the game

ANYTHING is viable

I am playing a mage as an Imperial, and having no trouble at all. I don't think you'll need an "optimal" race to play a mage. Plus the Khajit's strengths will help you plenty.

My first character is a khajiit and it starts with flames and heal, so yeah I'd say so.

I am playing as a Redguard mage. Definitely wasn't easy in the beginning, but by level 8 I was doing decently, and at 10/11 on I was all set. Even if you intend to be a pure mage once you get over the hump, I'd strongly suggest using one hand whenever it is needed for the first 10 levels or so... I remember that getting me out of a lot of binds.

Once I hit 10 though, I stopped using melee attacks altogether. I'll probably pick up one hand again around the 30's or 40's for some variety, but it definitely won't be a necessity.

Khajit have the 15 damage melee attacks, so they are great for when you run out of magicka early on. I've been playing one all day and it's working wonderfully for me, as long as I avoid monsters that can 1 shot me.

Every race/class combo is viable.