Would a lost phone still show as offline if someone found it and erased it? I lost my phone and it looks like it was either turned off or died at 5:41pm. When I use Find My Phone, its says offline.  

Is this because it's off or is it possible someone erased my phone? If someone erased my phone, would it still show up as offline, or would it disappear? 

I'm trying to figure out if someone has my phone or if it is just misplaced.
Yes, if a device has been restored, Find My iPhone will be deactivated and the device will show as offline. If you have iOS 7 or above, you will receive an email if this occurs next time the device communicates with Apple's servers.

However, with iOS 7 and above, attempting to erase an iPhone with an active Find My iPhone will enable Activation Lock. This means the device will contact Apple's servers and be available to you. Activation Lock can't be bypassed without your Apple ID.