You can not use 'Gratitude' as a statement of gratitude. Yet statements of gratitude are "thanks' and 'thank you."

You are thanking someone when you say "Thanks" "Thank you" Is another way to say "thanks". You show gratitude when you thank someone. You are grateful. You are telling someone they are very kind or generous. You are thankful so you show gratitude by saying "thank you so much".

"thanks' and 'thank you." mean the same thing. You could say: Thank you so much, I owe you a great deal of gratitude.[ meaning you are grateful for the help you received]