Industry is usually one of the major deciding factors in a victorious outcome in war.

true false

That seems more of a question for discussion than a true-false assertion. "Usually" and "one of the major factors" already hedge the statement in such a way that calling it clearly true or false would be problematic. And the history of warfare can show examples from either side of the equation. In the US Civil War, the North's industrial advantage was a significant factor in its favor. On the other hand, in the United States pursuance of war in Vietnam, the enormous industrial strength of weaponry that the US could bring to the war could not defeat the determination and resilience of their highly motivated opponents in Vietnam.

If "usually" and "one of" the factors are in there as a hedge, I suppose you could assert the statement as true, but again, it seems to be a question more fitting for discussion and defense using historical examples.