Here is a pension credit calculator.
https://www.gov.uk/pension-credit-calculator
If he pays tax depends on his total income, if he retires completely so his only income is pension credit he will not pay tax. His occupational pensions will be deducted from the pension credit £ for £, so he will get pension credit minus the £93 . If he had never bothered paying into a pension he would get the full pension credit with no deductions makes you wonder why anyone bothers paying into a pension !
If he gets pension credit he also automatically gets 100% housing and council tax benefit, 100% free dental treatment, winter fuel payment, cold weather payment, free travel to hospital and medical appointments and a lot more so it is well worth claiming.