Will my data have remained on the iPhone 6s after restore?

Basically I made sure to disable find my iPhone and sign out of iCloud. I didn't sign out of my Apple ID and I read on Google that if you're going to sell or give away an Apple product you need to sign out of both Apple ID and iCloud. Anyways so I signed out of iCloud and made sure find my iPhone was disabled, then I went to general and erased all of my content and settings. The process went fine however, I'm worried that when my brother set up my phone it asked him to input my iCloud or Apple ID information, which he knows and then he will be able to see all of my past messages and photos. Could this of happened. If anyone could let me know as soon as possible as I've been extremely anxious about this for a while now.