The technique used to get up wind on any board depends on how much power you have in your sail. If you are fully powered, sinking the leeward rail and "riding the fin" will give you maximum pointing ability. The wider the board, the less pronounced the dropping of the leeward rail. This only works if you have full power, and sheeting in is good to a point. You can over sheet and stall, so practice is important. Closing the gap depends on your sail and board, but in general terms, yes, you want to close the gap too.
If you are overpowered while pointing, sheeting out will decrease the power and you will lose some speed and possibly gain some control, but if you are on a wide board, sheeting out also takes the weight off the mast foot and you may risk taking off (wind under the board). This is a big problem for formula boards as you must keep mast foot pressure on all the time or you could send the nose of your board straight up. On a formula board in a big gust, you just have to keep the sail powered and hang on. If you chicken out = disaster.
In less than fully powered conditions and planing, riding the fin is still possible, but your upwind angle will be much less pronounced. If you can't ride the fin (barely planing), then the "lower the windward rail" technique is necessary, even if you are slogging.