He can't tack upwind with a kite. It is a down wind sail.
You might want to change that block to one with a swivel in it, so that line runs freely and not chafing.
You can't tack upwind with Outleader kites, these are the ones which were(and are?) briefly used in (conventional)sailing and somehow recognized by the ISAF(?).
With kitesurf kites however, even by means of just edging the kite board into the water (instead of using a more effective foil like a keel or dagger board), you can do considerable upwind travel, otherwise kite surfers always had to be pulled upwind by someone before following their passion and their sport wouldn't be popular at all, I suppose.
The kite I am using can generate easily directed pull pointing towards any direction from dead downwind to about 75deg off the downwind direction and it is very easy to transform this pull into upwind travel.
I can reasonably fast point up to 60 deg off the true wind with my construction, which I can easily proof with GPS-Tracks, if you want me to.
This is with a home-made and definitely not perfect prototype operated by a not quite experienced skipper, as I myself are still a beginner in operating my own invention, so even better performance should be possible.
I have tried other blocks but there were some issues so I changed the setup and the line wear caused by the chafing seems to be acceptable thus far.