The answer depends on the use of the gas.
IF the gas is part of your 17025 accredited test result (MUA chain), or part of calibration for instrumentation that is a 17025 accreditation (MUA chain), then yes it must be accredited to ISO 17025.
ISO 9001 certified gas is sufficient for safety monitors that are not part of your test/calibration process, and is sufficient for any testing/calibration that is not part of your ISO 17025 accreditation.
Yes, we have ISO 17025 accredited gas we use in our testing process.