Haha... It's just a "funny" way to say 살아요....
You can say 살으삼 in real life too with your voice, but usually it's used for texting.
I recommend you to always say 살아요 though.... because 살으삼 is grammatically wrong. :)
You'll see many other strange-looking words like this online or through messengers.
I want to give you an example in English.... but I'm not sure it'll be a good example for you... haha.
For example..... Someone might say, "Whatcha doin'?". And, a Korean will go, "What does it mean.....?". And the person will say, "oh, I'm sorry. It means 'What are you doing?'."
Or.... spelling "girl" like "gurl" or "gal".
Use proper Korean if you like to use proper English. :)