"而且比这多得多" can be translated into English as "and it's far more than that" or "and it's much, much greater than this", depending on the context and the specific quantity being referred to.
For a more natural and concise expression in many cases, "and it's way more than that" could also be used informally.
Here are a few examples in sentences:
1、 The actual cost is far higher than we initially estimated, and it's far more than that.
（实际成本比我们最初估算的要高得多，而且比这多得多。）
2、 The number of participants exceeded our expectations, and it's much, much greater than this.
（参与人数超出了我们的预期，而且比这多得多。）
3、 I thought I had a lot of work, but hers is way more than that.
（我以为我有很多工作，但她的比这多得多。）