Arrow season 3
Oliver fights Ra's al Ghul in the midseason finaleThe CW (official stills)

During the Television Critics Association's winter press tour panel, "The Heroes and Villains of Arrow and The Flash," held on 11 January in Pasadena, California, Arrow star Stephen Amell revealed some interesting details on the upcoming episodes of Arrow and the return of his character post the shocking mid-season finale.

Amell shared that he knew prior to going into Season 3 about his battle with Ra's and the outcome.

"I personally love when there's adversity for the protagonist and when we give other characters on the show the opportunity to acquit themselves and to come more into leading roles. If we don't give other characters the opportunity to shoulder the load, then we give nothing for the viewers to attach themselves to. ... I'm excited for everyone's opportunity," he said. (via channelguidemagblog.com)

While the recently released synopsis (below) of Arrow season 3 episode 15 has confirmed that the show's lead star is alive, it's unclear as to how he survives and escapes death. After the mid-season finale, several fans came up with the theory that The Lazarus Pit - a natural phenomenon in the DC Comics that possesses restorative properties that instantly heals injuries - will be instrumental in reviving Oliver. However, Amell seems to have ruled out that option:

"We just saw him fall. We've seen Oliver survive, so whether he went straight off the cliff, whether something broke his fall, whether he hit the ground, whether there's — we have mystical herbs on the show that have healing powers. We've seen the Lazarus Pit, although that's not something that's going to be used for Oliver. I hope he survives. I like playing him."

Arrow season 3, episode 15 'Nanda Parbat' synopsis:

After being revived by Merlyn, Oliver must escape Nanda Parbat with help from an unlikely source. Laurel and the rest of Team Arrow receive shocking news about Ray Palmer and his true intentions with the A.T.O.M. Suit.

Check out Oliver and Ra's al Ghul's fight scene from the mid-season finale episode: