Can an unemployed husband be ordered to pay maintenance?

Yes, Mere unemployment does not automatically relieve a husband of his legal obligation to maintain his wife, Courts don't simply take "I have no job" at face value if there's evidence the husband is capable of earning, for example he's qualified, healthy, and has just chosen not to work, or he's hiding income. In such cases, courts can impute a "notional income" based on his qualifications and earning capacity, and order maintenance based on that.