A South Gate man who admitted committing more than a dozen armed robberies targeting people leaving local casinos with winnings is set for sentencing Thursday. Dereck Nathan Lopez, 22, pleaded guilty in June in Los Angeles federal court to a single count of interference with commerce by robbery. A co-defendant, Juan Gabriel Gonzalez, 23, also of South Gate, pleaded guilty to the same charge and is scheduled to be sentenced in October. The 10-cou…