x filing deadline yesterday in the US. A few days for refunds to get to accounts, another few days to get to an exchange...
Most people expecting refunds already have them. Yesterday was for the people paying net taxes.
It's a kind of graphics card that's used in a rig. I can't speak for mining profitability of bitcoin during that timeframe, but if he mined and held litecoins with his 7970's he would have made a killing.
A pair of 7970's would have mined about 150 BTC from Jan. 2012 to Jan. 2013, worth about $2000 USD then but almost $75000 USD now.