That is really a multi faceted question.
THE PCI Compliance of eCart is dependent on the PCI Compliance level of the server it is hosted on.
The main factor in PCI Compliance is the server.
The application you create using eCart cannot be PCI Compliant if the server does not reach PCI Compliance standards.
if your environment is PCI compliant, then the application created using eCart can be created to be PCI compliant.