I am worried about my facial fat graft recovery. Will a soft bump on the cheek kill my fat after 9 days from the surgery date?

It is unlikely that a bump will kill your fat.  Lack of blood supply and circulation to the area as with compression, can kill it.  It is hard to predict at this point which fat will stay and which will get absorbed.  It may take 3 months for everything to heal and for you to appreciate the final results of your procedure.

The best thing to do is wait it out.  There is nothing you can do to reverse the bump.  The fat is now trying to establish a blood supply and time will tell how successful it will be.  In general the face is very forgiving with "bumps" because it has such a good blood supply. 

There is nothing you can do at this point, just leave the area alone unless you see a large bruise.  If there is significant swelling, an NSAID is good to help bring this down.  Otherwise you have to wait and see what happens.  Best, Dr. Emer.