what happens to the saved passwords and accounts after erasing the ipad?

Yes, of course - where do you think they are kept if you erase the disk they are on and do not have a backup? You can use an online password manager, but I also keep a record of them where I can find them (I also keep 3 backups).

Passwords to what? Online websites? Hopefully you kept a record of them - unless you made a backup before erasing the iPad, they are not kept anywhere.