Do they EBT cards ?

I do not know but you can go his site

From their website[1]: Costco accepts all Visa cards, as well as cash, checks, debit/ATM, EBT and Costco Cash Cards. Photo identification and approval by a supervisor or manager may be required. A valid government-issued photo ID is required if you plan to pay by check. Cash, checks and EBT are not accepted at Costco.com, Costco Gas Stations or Costco Car Washes. [1] https://www.costco.com/member-privileges-conditions.html