Yes, it is.
There is no way you can know this but even if you're right, you're missing the point of lowering tax rates. There is every reason to believe, if you know economic history, that revenue will INCREASE following a tax rate reduction as the economy expands and more people pay taxes. The rich in particular tend to pay more tax revenue following a tax rate reduction. Bottom line, lowering tax rates, even with all the loopholes, will result likely result in more revenue.
Whether we add to or reduce the debt is ENTIRELY a matter of spending. That's also on Congress to fix or not.
There is a massive flaw inherent to this argument.
Based on the very same conservative theory that gave us this idea, the Laffer Curve, there is a point where lowering taxes stops raising revenue.
That is why it is called the Laffer "Curve" rather than the Laffer "Slope".
The apex of the Laffer Curve was reached during the Clinton administration, and has providing diminishing returns ever since, to the point where now we've reached the low point on the curve, and can no longer get a reward from lowering taxes any further.
Therefore, lowering taxes any further will LOWER total revenue, not raise it.
And that is according to right-wing theory, which I am not willing to admit is correct, but which Mitt is most assuredly referring to in his assertion that lowering taxes will raise more revenue.
A book written by the very same Arthur Laffer that developed the curve I was referring to.
Unfortunately, Arthur refuses to admit that, by his own math, lowering taxes will not raise revenue.