A Rockstar North CV has indicated that GTA 5 will be released in October and that Rockstar is planning on showing off the game in a new trailer very soon.
The CV, which was picked up by GTANetwork (via OXM), belongs to Jolyon Orme, lead vehicle artist on Grand Theft Auto 5.
Orme is the second Rockstar employee to suggest the October launch. In April a CV belonging to Alex O'Dwyer, an animator working at the studio, also mentioned the game would launch in October.
The closest thing we've got to an official indication on the GTA 5 release date was provided in Take-Two's financial guidance report for the current fiscal year ending March 31, 2013, where it implied the game was on track for release by April 2013.
Until we get something concrete from Rockstar or Take-Two we'd take this with a pinch of salt.