Yes, education vouchers help fight economic and educational inequality, because they allow poor students to have a choice in education. If a student is in a poor district, they can choose to go somewhere else. The funding can pay for a private education. There will be more private schools to meet demand.
No, I do not think that vouchers help with fighting educational equality when it comes to ethnic and economic conditions. Vouchers just move students to a school that is performing it well which increases the student to teacher ratio and then makes that school have new problems. These problems should be fought locally without vouchers.