About 13 million fewer people are without insurance than before ACA, that's a 1.3% decrease in the amount of uninsured people [1].
ACA marketplaces will insure about 13.1 million people in 2017 and insured 12.9 million in 2016. The rate of private insurance increased 1.2% from 2014 to 2015 and the rate of public insurance .6%.
Now, how much of this is due to ACA and how much is due to other factors is really impossible to separate. Almost anything would be pure speculation. Interestingly, premiums on the exchanges are climbing slower than private insurance [2].
Health insurance premiums had been rising for years, probably due to several issues: aging population, rising costs of equipment and pharmaceuticals, administrative overhead, tort, etc, etc. Additionally, ACA added some costs in the inclusion of pre-existing conditions. I don't disagree that something has to be done, but getting rid of ACA is not going to be a panacea.
[1]:https://www.census.gov/library/publications/2016/demo/p60-25...
[2]:http://www.latimes.com/business/la-fi-obamacare-premiums-201...