Right after Kane discovered the Xenomorph egg cluster things went downhill. First of all, his suit was ruptured. Next, he was embraced for a long time in an oxygen poor environment before he was dragged and hauled back to a breathable atmosphere. How did Kane breath after the facehugger breached his environmental suit?
From Wikipedia (emphasis mine)
Upon making contact, the facehugger tightens its tail around the host's neck in order to render it unconscious through oxygen deprivation. The facehugger then inserts a proboscis down the host's throat, supplying it with oxygen while simultaneously implanting an embryo
The how part is not covered in the film but it is definitively explained by ash when he was talking to Dallas that the face hugger was keeping Kane alive.