Kia Sportage 2003 won't start. Would head gasket cause such a problem

My brother in law has a 2003 kia petrol. The car cut out while he was driving (I wasn't there) after that it wouldnt start and had yo be towed home. Since then we have tried to tow start it twice without success. Brother in law says he spoke to a mechanic who said it sounded like a head gasket issue (I disagree and might be wrong but I thohght this would nt cause car not to start nut would cause smoking and overheating)

I have Torque pro android app which we connected and it brought up code p0304: cylinder 4 misfire detected. An internet search brings up camshaft sensor issue. They are on a tight budget and stretched financially at moment

What do the jury think.