Evidence of Support : it can be any combination of the following :
_ Affidavit of support : form I134 for DV winners signed by a USC or LPR.
_ a job offer in the US : it is safer to obtein a job offer on the company's letterhead and notarized.
_ money in the bank ( on your name ), or other assets : see poverty guidelines for an idea of the amount. ( bank statement)
Also, education and english skills play a role as it will help in finding a job.
The immigration officer determines your potential to become public charge. So the more proofs you provide that you won't become one, the better for you.
For my own DV interview, I presented 2 job offers ( one for me, and on for my husband ), but the lady still wanted a bank statement.