Raul Bautista
A bank robber, and one of the faces Rockstar put on the cover art alongside Jason and Lucia.
Raul Bautista is described by Rockstar as a bank robber, which places him close to the vault sequence shown in the official screenshot set.
Why the billing matters
He is prominent enough in the marketing to appear on the cover art collage alongside Jason, Lucia and Boobie Ike, and again in the portraits Rockstar supplied for a Dazed feature. Rockstar's cover art is assembled deliberately and it does not carry minor characters. Everyone else in that collage is either playable or running a significant part of the story's economy.
For a character we know one job title about, that placement is the most informative thing available.
The bank robber problem
Grand Theft Auto V's heists were its most celebrated content and its most linear. They were set pieces with a planning menu attached, and they were essentially the only place in the game where a robbery mattered. Grand Theft Auto 6 appears to be spreading that out, with a reported three-tier store robbery system covering the low end and an evidence-based police system that makes any robbery a problem with a tail on it.
A named bank robber on the cover suggests the high end is still there. What is not clear is whether Raul is the person who teaches the leads how to do it, the person who brings them in on one, or the person they end up on the wrong side of. All three are things this series has done.
What is not known
Almost everything. Rockstar has given a name, a job description, two pieces of art and nothing else. How he connects to Jason and Lucia has not been shown, no voice actor has been confirmed, and he has not appeared in any released gameplay footage.
This page is deliberately short on claims. There is a lot of confident writing about this character in circulation that traces back to nothing.