My mom just found her cat with a bunch of thread hanging out of his mouth. She got it out, but isn't sure how much, if any, he has swallowed.

Any suggestions? I'm finding things online that make it sound like he'll be dead by morning, and others that make it sound like no big deal. Would giving him a hairball lubricant like Petromalt help? She's calling the emergency vet, but any other opinions would be helpful.