Each family member would need to apply for a visitor visa in order to come to the U.S. for a brief visit. The process is initiated by filing a DS-160. This family will likely have difficulty obtaining visas unless they can show strong ties to Gaza. You can read more about visitor visas at http://myattorneyusa.com/travel-visas.
Answered on Aug 22nd, 2016 at 4:14 AM