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.