Her father's earnings will not matter in deciding the maintenance amount.
Generally maintenance is an interim amount that a judge awards to wife to support herself till the time divorce is granted.
If she was working, educated and has capacity to earn for herself, you need to prove the same (through her education proofs, last income drawn in the last company) etc. so the judge will take that into account before awarding maintenance.
rest all is left at the discretion of the judge.
You need to give more background, like your earnings, etc for the members to give reasonable answers.
is your wife living with you, what are the grounds on which you are filing divorce will also matter