from oracle 12c it is possible to find out detailed information about gather stats job
in em you may find it at

or use dbms_stats.report_* to get info
detailed at https://docs.oracle.com/database/121/TGSQL/tgsql_astat.htm#TGSQL95102

I use it this way:

variable mystatsreport clob
declare
    begin
    :mystatsreport := dbms_stats.report_stats_operations(
    since=>SYSTIMESTAMP-3,
    until=>SYSTIMESTAMP,
    detail_level=>'ALL',
    format=>'TEXT');
    end;
   /

print mystatsreport

variable mystatsreport clob
declare
    begin
    :mystatsreport := dbms_stats.report_single_stats_operation ( opid => 11898,detail_level => 'TYPICAL', format =>'TEXT' );
    end;
   /
print mystatsreport

variable mystatsreport clob
declare
    begin
    :mystatsreport := dbms_stats.report_single_stats_operation ( opid => 11898,detail_level => 'TYPICAL', format =>'TEXT' );
    end;
   /
   print mystatsreport