My brother worked for a company that went bankrupt, so he was let go. He was making $56,000 a year at the time, as a software engineer. He was there for 8 years. If he applies to another company, and they ask for a salary history and a desired salary, would they hire him if he only asks for $30,000 a year? He wrote that amount down on his application.

Hard to say, most likely there will be 100 people applying for that one job, so he needs to stand out, be able to show them he is the best person for the job.

I guess I meant to say, if he is hired for the job, will they pay him $30,000 a year if that's all he asks for?

A tough question, but seems to me he low-balled a bit much.

He should at least put down what he needs, given his current financial commitments.

Personally I would have put down a higher number and negotiated from there.