Dear K.P.Mishra,
At the time of introduction of EPS on 16.11.1995, the service pension for those completed 33 years was 50%. In EPS for those complete 20 years' service or more will get a bonus of 2 years. Accordingly 33 years will be treated as 35. To get 50%, 35 is to be divided by 70. Hence the formula is derived. It has no connection with the duration/age of getting pension.
The duration of pension of a member is lifelong regardless of age of 70 or else. When the provision of return capital is introduced in 16.11.1998, there was an option to avail pension for 20 years and thereafter to pay Return of Capital. In this context for completion of 20 years we have to wait till Nov 2018. If it was paid with retrospective effect, there is a chance to stop pension towards this clause.
If the member fail to submit life certificate, the pension will be stopped. Remarriage of widow/widower pensioner also is reason of stoppage of pension. If the pensioner is not getting a satisfactory reply from EPFO, through RTI Act the reply may be sought.
Abbas.P.S