Hi Prashanth,
You can use VBFA table and get the invoice linked to a sales order:
Select from VBFA where VBELV = salesorderno and VBTYP_N = M (item level)
Then for the invoice you can check in VBRK-KIDNO which is your payment reference and if this field has a value then it is paid.
And you can also check this field VBRK-RFBSK = C which means the accounting document is posted.
Hope these informations help.
Thanks,
Naveen