If you lose your character, do not worry, it will be back if you make sure to handle it in this way.
DO NOT make a new character. This will overwrite your last one.
Basically your character is gone when the cloud goes down. It will be back, just be patient.
Also, DO NOT hit "Retry" when you fail to connect online. Rockstar has explicitly stated that this may delete your character.
If you are playing and suddenly everybody in the rooms leaves at once, the cloud went down. Sometimes you will still be able to play, but know that whatever you do will not be saved.
If you want to make sure everything is saved, then logout to GTAV every time you want to get offline by using the start menu.
Basically, the gist of this is: Don't overwrite your character slot and don't hit retry when it fails to load online. You will be sorry.
Sucks, but that's how it is. Rockstar has some sh*t to work out.
That doesnt work for everyone OP. I never made a new character, I stopped playing yesterday when I noticed the cloud went down and I got timed out of a session...I come back about 8 hours later late in the evening...everything is up and running and my character is completely gone...I checked this morning as well, still gone.