To get across the two gaps and the fire pit, you're going to have to use some special grappling techniques. Fall into the right pit and grapple the top left block of the right side of the pit. When you climb up you'll be on the wall and you'll automatically bounce off to the other side and up to safety. Walk across the fire (take damage), but don't fall down. Duck and grab the side of the orange platform (just press
once, don't move yet). Remember to hold
and press
and it should boost you up.