This is a question I found myself asking the other day – I had wiped my iPhone and then applied the greenpois0n Absinthe jailbreak, but I wanted to restore all my settings, apps, pictures and app data from my iCloud backup.
To my dismay, I found that most people were saying it was not possible and the only way to bring forward your backup would be to backup into iTunes and then restore that backup after the jailbreak.
However! This is not true, you can restore your iCloud backup AFTER you have jailbroken, and it’s really, really simple to do
1) (recommended) Wipe your phone and return it to factory settings.
2) Setup the phone as a “new device” and apply your jailbreak.
3) Run Cydia (it should now be on your phone) and make sure it is setup and functioning.
4) Go into Settings > iCloud > Delete Account to make sure you do not already have an iCloud account attached to your phone.
5) Now go into Settings > General > Reset > Reset All Settings. This will reset your device and ask you to set it up again, go through the options and when you get to the iCloud section choose to restore a backup.
6) You should now have everything from your iCloud + still be jailbroken!