Can your digital footprint be destroyed or does it remain active on the internet forever

It depends on what your family or power of attorney decides to do when you die.
By contacting Twitter family,or friends can download a copy of your public tweets and close your account.
In Dec 2009, with changes to their privacy policy, Facebook began deciding on your behalf  how comfortable you were about sharing your information and with whom, while your still alove and capable of deciding for yourself. Upon your death you won't only have to worry about Facebook setting up public default settings, you'll also have your family deciding whether they want to deactivate, delete, download or memorialise your account - to  do any of this they will need your username and password.
If MySpace recieve proof of death they will cancel a deceased account.
LinkedIn will do the same.
YouTube allows your heir or power of attorney control of your account and all the content.
Google+ and Gmail will provide account information to family at their discretion.
Ebay and Paypal, after recieving a certificate of death, will delete your account.
Match.com will block the acoount of a user that has died so that it is no longer visable and eHarmony will remain open until a family member or power of attorney contacts the site, at which point eHarmony will close the account.