You can add as many payment processors as you'd like and tie those to unique contribution pages: https://docs.civicrm.org/sysadmin/en/latest/setup/payment-processors/#setup-and-configuration.

However, the real question is reporting requirements. What are they? Are these non-profits all under a parent non-profit? If not, then they should have their own installation of Civi. If they are related, you could create a campaign for each organization and track the finances separately. Or use financial accounts: https://docs.civicrm.org/user/en/latest/contributions/key-concepts-and-configurations/#financial-accounts.

You can add as many payment processors as you'd like and tie those to unique contribution pages: https://docs.civicrm.org/sysadmin/en/latest/setup/payment-processors/#setup-and-configuration.

However, the real question is reporting requirements. What are they? Are these non-profits all under a parent non-profit? If not, then they should have their own installation of Civi so they can easily get their financial reporting right. The likelihood of incorrect reporting is high if you tried to shoehorn multiple orgs in one Civi. 

If they are related, you could create a campaign for each organization and track the finances separately. Or use financial accounts: https://docs.civicrm.org/user/en/latest/contributions/key-concepts-and-configurations/#financial-accounts.