Probably, but not in the finished draft
I contacted Bev Vincent, author of The Road to the Dark Tower: Exploring Stephen King's Magnum Opus. Here's what he had to say:
When I was writing The Road to the Dark Tower, I was working
from the first draft manuscripts of the final three books. I received
later drafts of books 5 and 6 in time to incorporate any corrections
or changes King made to the quotes I had pulled from them, but I did
not have the opportunity to see the revised MS of the final book
before my book went to press. So there are several quotes from The
Dark Tower in my book that do not reflect what was finally published.
I’m pretty sure that’s the case here.
So Vincent suggests that this quote was from a pre-publication manuscript of
The Dark Tower VII: The Dark Tower. This seems most probable to me, since the quote is sufficiently dissimilar to any existing one to be misremembered, and Vincent probably wouldn't fabricate it.
This makes sense in the apparent context of the quote. Jake has just killed several people, but he spares the dish-washer Jochabim.
“North of there, if you do like it or if you don’t,” said the
washerboy. “Will’ee kill me, lad? I don’t want to die, sad as I am.”
“I won’t be the one to kill you if you tell me the truth. Did a woman
come through here?”
The Dark Tower VII: The Dark Tower
According to Vincent in The Road to the Dark Tower, his thoughts are that Roland, Eddie, and Susannah would have killed him without a second thought, thus prompting the quote:
“I love them [Roland etc.], but I hope I die before it gets me so bad it stops
making any difference if the ones against me deserve [to die] or not.”
Certainly Jake seems a kinder character than Roland, so it seems likely this might have occurred in one of King's earlier drafts.
The quote is probably from the initial draft of The Dark Tower VII: The Dark Tower.