Hello Viesail,
Twice I've done repairs similar to the one you asked about.
Use epoxy for the repair and add a bit of interest to the job by drilling holes to insert dowel sticks down through the tiller. I used oak dowels of 3/8 inch diameter although I drilled the next size large hole with a bit...25/64. Using a drill press would be best, but acceptable results can be achieved with care and a hand-held electric drill. I chose to place the holes at 6 inch centers along the tiller, but stopped short of the forward end in case I decide that a tiller extension is needed.
The dowels add interest to the tiller and the epoxy on them serves to strengthen the split areas. By all means clean out the old glue as much as possible and use glueing clamps after the epoxy covered dowels are inserted. Drizzle some epoxy into the split areas before clamping.
The dowel in the pictures is extending from the aft end of the tiller. The dowel going through the tiller horizontally is to repair the hole for the bolt in the top of the rudder. It was oblong and I will drill a new hole to insert the bolt for installation.
Best Wishes, Phil