The entire chain all the way down is sanctioned, the US can and will climb up and down that chain to punish sanctions violations. A company like Disney will have to have a Sanctions Compliance Program and like any other compliance regime, there are standards, external auditors, etc. to make sure enough is being done, and "enough" can be a bit of a moving target. If you get caught having sanctioned suppliers, those standards and auditing get kicked up a notch, if you did a really bad job maybe fines or criminal charges.
There isn't ever a sense of "I'm doing enough and therefore the sanctions violations happening are no longer my fault". It's somewhat up to you to determine your risk and tailor your compliance program to address them and to adjust if you're ever wrong.
How guilty you are is a function of how good a job the state department thinks you're doing trying to avoid sanctions violations.