In my view, there is some good evidence that more guns increases gun-related violence. There's also a possibility that guns deter some violence. Everyone on all sides likes to pretend that they can measure both of these effects against each other, but that is almost always suspect.
The most careful analyses routinely find that, when you control for all of the variables that matter, gun control might help reduce gun violence but it would not be a panacea. The U.S.' high levels of gun violence and death are not actually only or even primarily due to our relatively lax gun laws or poor gun law enforcement. There are a ton of sociological factors, from ethnic heterogeneity and residential segregation to geographic patterns to a militaristic culture to income inequality. Those should be resolved primarily.