"而且比这多得多" can be translated into English as "and it's far more than that" or "and it's way more than this".
Both expressions convey the idea that the quantity or amount is significantly greater than what has been previously mentioned or implied. The choice between them may depend on the specific context and the desired level of informality.
"And it's far more than that" is a more formal and precise way to express the idea.
"And it's way more than this" is more colloquial and might be used in everyday conversation.