Q: iphone - icloud files missing

Did you backup the iPhone 4 and restore that backup to the new phone? If you did, how did you backup? iTunes? iCloud?

When it was the time you backed up your device? Did you use iCloud Photo Library so the photos are stored there? If yes, is iCloud Photo Library turned on in your Settings > iCloud > Photos > iCloud Photo Library ?

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

iCloud Photo Library FAQ - Apple Support

Get help with your iCloud Photo Library - Apple Support

Yes, there is a possibility that your photos are still on the old phone as long as it hasn't been erased.

Maybe you should explain the exact sequence of events that took place when you activated your new phone. Did you set it up on your own? Did your carrier set it up for you?

take a look at this support document that mabaeyens posted above

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

You are very kind to try to help your friend through this scenario, but it is really difficult to help him unless he can answer some basic questions on his own.