If I am a delegator on a validator pool that is inactivated, will I receive a reward? And how much?

Yes, rewards will still be distributed if a pool is inactivated during a staking epoch. Rewards for the current staking epoch will be accrued as usual.
The reward amount depends on how long the validator has been working, and the reward corresponds to the validator’s participation in consensus during the staking epoch.

For example, if the validator was working fine, didn’t disconnect their node, and produced all blocks they should have produced (went through all AuRa rounds during the epoch), its pool will receive 100% of the possible pool’s reward.

However, if the validator skipped half the staking epoch (only produced 50% of blocks they should have produced), their pool will receive 50% of the max possible pool’s reward. .
If a validator was malicious and was removed by the system for misbehavior, its pool won’t receive rewards. Pool rewards also depend on how much other participants staked into other pools.