Perfacile factu esse illis probat

[dova]

I am trying to understand the syntax of the following phrase:
"Perfacile factu esse illis probat conata perficere". The translation is "He proves to them that completing these efforts is easy to do" .
Since this is an Indirect statement, I am confused which is the Subject-Accusative . Is it perficere? but as an infinitive noun it is nominative - not accusative. Thanks.

 

[Pacifica]

Is it perficere?

Yes.

but as an infinitive noun it is nominative - not accusative.

Infinitives can have accusative roles as well.