I made it 6 opponents in before I was diced by a cleaver- the reward seems very low for that kind of endurance.

The reward is very low, considering the risk! For example:

A Duel Inept/Inept Entry 1c Win 5c (profit 4c),

And an Elimination Inept/Inept Entry 3c Win 1s 6c (profit 15c),

Clearly the absolute minimum profit for an Elimination Inept/Inept would be 5 * 4c = 20c profit.

Similarly:

A Duel Aspirant/Aspirant Entry 2c Win 10c (profit 8c),

And an Elimination Aspirant/Aspirant Entry 6c Win 3s (profit 30c),

Clearly the absolute minimum profit for an Elimination Aspirant/Aspirant would be 5 * 8c = 40c.

Except even if this is addressed it fails to take into account the risk involved in Eliminations (i.e., potentially starting each fight with ever-increasing permanent damage, and a loss of the payout if you wipe).

Therefore (using the mechanism above) I would recommend multiplying the current payout for Eliminations by a factor of about 4 to reflect the risk.

A better mechanism to handle the payout for Eliminations would be to make the payout a function of Duel payouts (at a given Tier/Rank):

Elimination Payout = f (Duel Payout).

For example:

Assume a Duel at a given Tier/Rank yields a profit of x,

Then the absolute minimum profit for an Elimination at the same Tier/Rank would be 5 * x = 5x.

Except this fails to take into account the fact that 5 wins must be achieved to obtain the payout. So assume the odds of surviving the Elimination are 50/50 = 50% (or whatever), then the payout would be doubled (in this case) to reflect this. So now the Elimination payout = 2 * 5x = 10x.

Except this fails to take into account the fact that you can't heal between fights, and the risk associated with having increased permanent damage at the start of each fight (increased risk of permadeath). So assume you're going to award an additional basic Duel payout (or whatever) for each fight in the Elimination to reflect this, the Elimination payout then becomes:

Elimination Payout = (2 * 5x) + 5x = 15x.

In other words:

Elimination Payout = 15 * Duel Payout (at a given Tier/Rank).

Having said the above it's worth bearing in mind that this is effectively an issue of balance, which therefore ought to be left until content is complete and bugs are fixed.