The funds have to be personal investment funds. Many investors will refinance their homes as a source of funds. Many use their salaries. With the right EB5 counsel, you can authenticate your funds for an approvable I-526 petition.
The investor will have to use their personal funds which can be borrowed from a financial institution for an EB-5 investment. However, the assets of the EB-5 business cannot be used as collateral for the loan amount.