iOS 6.1.4 on iPhone 3GS or iPod touch 4G

No. The iPhone 3Gs and iPod Touch 4 will very likely never get another iOS update and are currently at the end of their life cycle.

Sad but I think this is true.

No 6.1.4 was ONLY for iphone 5 but you can get ios 6.1.5 on the 3GS and ipod touch 4g which doesnt patch the jailbreak for 6.1.3

The iPod Touch 4g and iPhone 3GS have the iOS 6.1.5 and 6.1.6 update, both of those support p0sixpwn