While ETHGas affects all users on Ethereum, not all users directly interact with the protocol. For those indirect users, they may earn $GASS governance tokens and separately participate in ETHGas' share of Staking Fees where 30% of transaction revenues are reserved for the ETHGas Treasury's continued operations and up to the remaining 70% being distributed to stakers accordingly.
There are two multipliers for Indirect Users: Base Multiplier and Time Multiplier
The Base Multiplier:
ERC20 Token Stakers earn 1x share of rewards
ETH and ETH Variant Stakers earn a 2x share of rewards
$GASS Stakers earn a 10x share of rewards
The Time Multiplier:
Rewards are a function of the staking-time, that is, the longer one has staked, the higher rewards one is entitled to. This is calculated as a weighted-average stakign time since the day of launch.
See this spreadsheet for example calculations