My new iPhone 6 will not sync via iTunes..

What exactly happens when you try to sync?

Does iTunes see the iPod?

Was the iPod previous synced to another iTunes library/computer?

Have you successfully synced from this iTunes library/computer before?

If so have you done anything like update iTunes on the computer since it last successfully synced?

Do the songs play in iTunes?

Does any media now sync to the iPod?

Do you have the right boxes checked to sync?

iTunes: Syncing media content to iOS devices and iPod

Try syncing using the manual method

Managing content manually on iPhone, iPad, and iPod

Last, backup and then restore from backup. See:

iOS: Back up and restore your iOS device with iCloud or iTunes

I don't know if anyone has figure out this issue, but I just spent about 2 hours with apple. I have an old computer with 10.6.8 and cannot upgrade itunes or OS anymore. We did everything to sync my iPhone 6 128GB it didn't work. Until, I totally deleted itunes from my computer and got the latest iTunes I could get again on my computer to download 11.4. I then Tried to re sync my phone with a couple of songs first. Now, I can manage everything again from my older computer thanks to Apple. Hope this helps.