The film's official novelisation (considered a canon source of information about the movie) indicates that yes, Poe's mind was indeed violated by Ren using the dark side of the Force to read his innermost thoughts and discover his secrets.
Slumped and shackled in the seat, Poe was still breathing. Beyond that, he no longer cared much what happened to him. It wasn’t his fault, he kept telling himself. For an ordinary person, no matter how strong they thought themselves, resisting the probing of a creature like Kylo Ren was simply not possible. He had tried. There was no shame in the failure.
The junior novelisation also gives a pretty solid account of what transpired
He reached toward the prisoner with gloved fingers. Through them Ren channeled currents of pain from his own bottomless well—and tendrils that would probe the depths of Dameron’s weak mind.
“Tell me. Tell me.”
