Brian of nzolivers.com generated the following search results of official BDM Historical Records showing children born in New Zealand to Louisa and Samuel:
1875/9161 Gates, Ernest Louis
1876/11311 Gates, Frank
1878/14616 Gates, William James
1880/5341 Gates, George
1881/11799 Gates, Ada
1884/6932 Gates, Gertrude Jane

Name and year of birth from above BDM Historical Record.

From the 1923 Wise’s New Zealand Post Office Directory, Greytown section:
Gates, F. labourer

From the 1926 Wise’s New Zealand Post Office Directory, Greytown section:
Gates, F. labourer

Month/year and place of death from New Zealand, Birth Index, 1840-1950

Date of death of 19 August 1930, aged 53 years, from billiongraves.com website for Greytown Cemetery. Buried alone. Maybe was never married?