My question is simple. If I cut off the non-flowering branches, will it force the plant to put more resources into the already growing fruits?
More specifically, my tomato plant is growing beyond where I can contain it. A cage thing isn't an option. So I was wondering, can I cut off the shoots that are growing out of bounds, and would that force more resources into producing the fruits?
You can certainly cut off (prune) what is growing where you don't want it.
Of course, rather than "force more resources into the fruit" that will remove area for photosynthesis, so there will be less resources, overall. But in general, tomatoes can be pruned fairly hard without undue consequences. They get rather jungle-y if left to their own devices. It's common, for instance, to prune them down to a single stem and train that on a stake or twine.
As the end of the growing season looms it's good to cut off flowers, so that the resources from the remaining leaves are put into already developing fruit, rather than into new fruit that will not ripen before frost; but that's a different question than the one you have asked about cutting off non-flowering bits.
