是的.这是祈使句,前面省略了You should,you是被省略的主语.
Let（谓语） those people in need（宾语） understand that we will go all out to help them out of poverty（宾补）
in need是后置定语,修饰people.
that we will go all out to help them out of poverty是understand的宾语从句,做understand的宾语.understand that...组成省略to的不定式短语做宾补.