The 8th Pay Commission's recommendations might be important for those who have already retired. Pension matters are part of the commission's job. If the government brings older pensioners under the new structure, their monthly pension could increase. And if the revised pension is applied retrospectively, there's a chance they'll get pension arrears based on the difference.
But there's no official word that every pensioner will get this benefit automatically. The math for pay and pension arrears will be different.
For working staff: It's the difference between the old basic pay and the revised basic pay, plus applicable allowances.
For pensioners: It's the difference between the old pension and the revised pension.
The amount you get will depend on the fitment factor, pay level, start date, and the government's rules.