Does the energy the top load of a spark gap tesla coil discharges have enough amperage to kill you?
First , there is no certainty. People have survived contact with tesla coil arcs, and people have died. So, any time you plan to do it, you have to ask yourself 'do I feel lucky?'.

While the current in the arc from a tesla coil topload is low, it can damage you, and it can kill you.

Damage can be caused by RF burns, both on the skin, and in nerves below the skin. 

An arc is a continuous channel of hot plasma. This can conduct an arbitrarily large current, if the power supply is capable of supplying it. Unfortunately, tesla coils tend to be operated in the vicinity of mains cables, whether trailing over the floor to reach the coil, or fixed to the walls of a garage. If an arc from the coil hits both you, and a mains connection, the mains supply is capable of sending a lethal current through the arc and through you. This is how a performer died on stage demonstrating a coil, taking arcs to the hands. The arc also struck a lighting cable strung above the stage, and he was electrocuted.