The incident at the Watergate Hotel was the biggest scandal in US governmental history. "...gate" has become something to indicate a large scale scandal in a government or corporation where the corruption goes clear to the top.
It is sort of like adding "Mc..." (in reference to McDonalds) to the beginning of any word to give the meaning that it is cheap, American, mass produced and tasteless.
For I am convinced that neither life nor death...neither the present nor the future nor anything in all creation will be able to separate us from the love of God that is in Christ Jesus our Lord. Romans 8:38-39