Look at the volume column and you'll see that Tether has more volume than bitcoin and has had for a little while.
Tether has recently
a) Admitted that they don't have 1:1 backing in USD
b) They use customer funds for investment rather than just storing them and
c) They're currently under investigation by the New York Attorney General.
Against that backdrop they've increased the number of Tethers in circulation by $400 million in the last month...
Now it's possible that they've got a load of companies who really believe in them to the point that they're eager to invest in Tether (even when there are other 1:1 backed stablecoins available)
A different interpretation could be that Tether have worked out they can effectively just print money as much as they want and are using this to buy bitcoins, driving up the price...