Is Iphone 5s screen scratch proof or do I need to get a screen protector

No glass is scratch proof.

I have never used a screen protector and never had a problem.

You may use one if you wish.

I personally would recommend a screen protector for it. It keeps the phone looking nice for a longer period of time and boosts the resale price if you ever wish to sell it. If the rumors hold true and the iPhone 6 uses sapphire glass then it could very well be scratch proof or very nearly so.

I've never had a screen protector on any phone in close to 7 years. My screens have never shown the slightest hit of scratches. Screen protectors defeat the oliophobic coating that prevents most fingerprints, and many of them can never be removed without leaving a residue. If you plean to keep the phone in your pocket with your keys you might want one, but that's a really bad idea anyway because it can result in more serious damage to the lightning connector, the camera lens and the flash.