Your question was not about lives in general which you don't seem to care about, but: "...how many Palestinians lives were saved during indiscriminate bombing attacks by those tunnels?"
I'm not sure, but I am sure that Jewish lives were saved, (sorry) and if all goes as Israel hopes, countless Palestinian lives will be saved as well.
How many civilian Palestinian lives we sacrificed building and protecting the tunnels?
How many dead do you want? When will you call for Hamas to surrender and release the hostages?