Rockstar said they wanted GTA Online to expand overtime and it seems they are doing just that with tons of new content coming in the future.
It appears that someone went into the GTA game files after the recent Beach Bums update and found brand new audio from characters talking about new content. I'm not sure if he was the one who hacked it but Youtube user Franken Stein uploaded the 7 minute video containing all the new audio.
The video features snippets from all of the GTA online characters you take jobs from including Lester, Dom, Ron, Gerald and Simeon.
Here is a list of the new content which the characters mention themselves
