According to Digitec, yes, because in the HAF X Bigtower the length is in the specifications:
Max. Length graphics card i 342 mm
And the length of the graphics card is also stated:
Length 32.70 cm
Why the dimensions of the card are given in cm and those of the enclosure in mm is also a mystery to me, but you should be able to do this conversion in your sleep...

It took me exactly 6 clicks to find out.