Evidence of Support : It can be any combination of the following three :
_ Affidavit of Support : form I134 filled by a US Citizen ( USC ) or a Legal Permanent Resident ( LPR = GC holder )
_ Job offer in the US : it is better to obtain a job offer on the company's letterhead and have it notarized.
_ Own funds ( bank accounts, assets....): see poverty guidelines for an idea of the amount. ( bank statement)
For the Evidence of Support, you can provide any combination of the 3, which means you can provide one ( any one ) of the mentioned documents, two ( any two ), or the three of them.
Remember that you better be safe than sorry. Bring as much as you can.
So, the I134 alone is good. Still, it would be better if you could show your own funds.
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.