Developer and noted iOS beta hacker Hamza Sood has discovered code relating to Force Touch in iOS 9. Sood tweeted out a screenshot of the code this evening, saying it appears Apple has been "testing keyboard trackpad gestures on the iPhone 6s, activated via Force Touch."
Given that the 6s is expected to be unveiled within the next few weeks, and believed to already be in mass production, it would seem the code all-but-confirms that the new iPhone will include Force Touch technology—a feature that already exists in MacBooks and Apple Watch.