From the article, there are about 200,000 people with income of $1M+. Let's make it $5M per person. That's 1 trillion USD combined income.
The rest of the taxpayers seem to be about 200,000,000 with an average income of about $25,000. Combined income = 5 trillion.
So, if they reduce the tax of the bottom group with 2%, as Mr. Buffet suggests, the tax of the upper bracket has to be hiked with 10% just to compensate. And if we add another 10%, just for the fun of it, that's 100 billion taken from the rich but it's still a measly part of the budget (around 3 trillion) not to mention the debt (15 trillion). And don't forget that people with 1M+ income have a vast number of legal and semi-legal tricks at their disposal to reduce their tax rate. The moment you increase the tax too much, you start seeing money flowing to offshore locations.
So, while "tax the rich more" and "let them share the burden" are great feel-good slogans, I don't think they offer any practical solution for the huge USA deficits.