Does the iPhone ask for iCloud password after updating to iOS 8.1? I forgot the password of my iCloud account. I'm using iPhone 4S I am afraid that if I updated to the new iOS, the phone will be locked and I wouldn't be able to use it. P.S. I have tried iForgot to restore my password, but it didn't work out as it keeps telling me that my answers are wrong.
Yes, you will be required to verify your account when you first log in. 

I would suggest trying to get to the bottom of it BEFORE you upgrade, it will be harder after (since you should still have some access to email accounts etc).

Also, I would research the effects of running iOS8 on an iPhone 4S. Although it may be supported, I would think it would be incredibly slow.

I know you didn't ask for the second part of this answer, but I would strongly recommend you do some more research on this before blindly doing it.