Although I only play LoL and no DotA/DotA 2 (yet) it looks like
at the moment the same mechanics apply to both games in DotA2 you earn more gold since the October 04th 2012 Patch. I found the following here for the original DotA and here for DotA 2:
Gold for a Kill
Every time you kill an enemy hero you are awarded with
(Current Streak of Dying Hero)+200+(Dying Hero's Level)*9 reliable gold. Where current streak is:
- 0 if the hero has no kills since last respawn
- 0 if the hero has killed another hero and not died yet
- 0 If the hero has two kills in a row
- 50 Killing Spree (Three kills in a row)
- 100 Dominating ( Four kills in a row)
- 150 Mega Kill! ( Five kills in a row)
- 200 Unstoppable! ( Six kills in a row)
- 250 Wicked Sick( Seven kills in a row)
- 300 Monster Kill!!! ( Eight kills in a row)
- 350 Godlike! (Nine kills in a row)
- 400 Beyond Godlike! (Ten to infinite kills in a row)
This means you can get up to 825 (400+200+25x9) gold for a kill if the hero was Level 25 and had more than 10 kills since his last death.
Gold for an Assist
Heroes that are in a 1000 area and not being the killer will be granted a certain amount of reliable gold, depending on total heroes (including the killer) in that area.
- 2 Hero: 125+12*(Dying Hero's Level)
- 3 Heroes: 40+10*(Dying Hero's Level)
- 4 Heroes: 10+6*(Dying Hero's Level)
- 5 Heroes: 6*(Dying Hero's Level)
Assists only give gold if Dire or Radiant gets the kill.
As 25 is the max. level for heros this means you can get up to 425 (125 + 12 * Level 25) gold if you're the only hero besides the killer in a range of 1000.
For loosing gold it's a bit more complicated, because your aquired gold is split into 2 categories:
- Reliable gold - Any bounty you get from hero kills is added to your reliable gold pool.
- Unreliable gold - Everything else (creep kills, neutrals, etc).
The difference between the two (except from how each is earned) is how each one is spent: Dying can only take away gold from your unreliable gold pool and not from your reliable gold. Buying items uses up your unreliable gold first before using your reliable gold. Buyback uses reliable gold first. In the end you still have a fixed amount of total gold (you just add the two together).
And further below on the pages you can find:
Every time you die you lose 30*(Level of your Hero) unreliable gold (Dying cannot take away reliable gold), the only way to reduce this amount is with a Bloodstone - you'll lose 25 gold less for every Bloodstone charge.
Please note that DotA 2 is currently still in its Beta phase (still in development), so its mechanics may change until release!