I'm American, but lived in Istanbul over a year, about 4 years ago in my mid 20's, and have been back 4 times since, including living there as recently as this past summer from June-August.
The cameras are not in every bar or street corner, though most establishments do have their own private ones, I certainly wouldn't say all private establishments do. There is a difference too btw cameras owned by an establishment, and cameras funded by the city.
The main cameras in Istanbul are in the high traffic tourist areas and are a very sophisticated attempt for law enforcement to cut down on and monitor crime. There was a lot written about them in newspapers when they went through the effort of installing the city cameras because as I mentioned its a pretty sophisticated system. So most locals would know and be aware of the areas the cameras are numerous. They are not hidden by any means, so if you are looking for them you can spot them. But if you aren't looking for them you might not notice them.
However as numerous as they are in high traffic areas, it should be noted that Istanbul is a very large, and VERY spread out city. So these cameras are not city wide. Though they would be numerous in the areas Sarai most likely frequented.
I hope that answers your question.