The makers of GTA 5 will not be attending E3 this year.
In case there was any doubt left, the studio itself has just confirmed via Twitter that it has no plans to attend the Electronics Entertainment Expo (E3) in any capacity whatsoever. Despite what "some sites" (Rockstar's words, not mine) are reporting, the studio has previously omitted itself from attending the event and this year will be no different.
Rockstar made the comments in response to a question about whether they would have something to show at the event.
@blouw19 Despite what some gaming news sites may be reporting, we will not be at this year’s E3 expo.
— Rockstar Games (@RockstarGames) June 4, 2013
Likewise, their parent company 2K Games will not be attending E3 this year, either. However, unlike Rockstar, 2K Games will have meeting rooms at the event.