Answer
(Fatwa: 374/268/D=1433)
If that Hindu person is investing with you in the business while he has taken interest based loan from someone else then in this case the money taken on loan by him carries no harm. You can invest in the business, it is lawful. It is his personal action to pay interest on loan, this neither create any problem in the money taken on loan nor there is any harm in investing this money in your business.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband