The ending

He survives and marries Jenny.

He dies because of the Hays Code, and because he isn't cut out to be a social worker.

In the film he turns his grifting, gambling and thieving skills to good use for the benefit of the settlement house, but wouldn't tensions inevitably arise when Jenny would want him to walk the straight and narrow?

And the aforementioned skills required the most stringent kinds of punishment under the Code - in this case, the death penalty.

we don't know