GTA Online came out about 2 weeks after GTA 5’s original release. GTA 5 launched on September 17, 2013, and GTA Online launched on October 1, 2013, so the gap was 14 days.

Release gap

  • GTA 5 release: September 17, 2013.
  • GTA Online release: October 1, 2013.
  • Time between them: about 2 weeks, or 14 days.

Extra context

Rockstar framed GTA Online as a separate online component that followed shortly after the main game, rather than launching on the exact same day. That short delay was meant to give players access soon after story mode released.

TL;DR: GTA Online arrived two weeks after GTA 5.