Correct me if wrong but with a LvL 8 character (2 fighter, 3 warlock, 3 sorcerer) and curious to know if this is legit in combat.

Character has its warlock familiar touch the target and uses inflict wounds ( 3d10 + 1d10 for each slot level above 1st.) from divine soul sorcerers origin then uses action surge to use it again and finally metamagic to caste eldritch blast ( 2d10 ) as a bonus action.

That stated if using 3rd level spell slots for both inflict wounds plus the eldritch blast would equal 12d10 on a single turn?

This would not work for 2 reasons:

1. When you cast a spell using a familiar it must use its reaction to deliver the spell - the familiar only gets 1 reaction per round, so once used you will need to wait until your next turn to deliver a spell through it again. 

2. If you cast a spell as a bonus action - regardless of level or type of spell - the other spells cast that turn can only be cantrips. 

Quote from Ronnie_Soach >>

That stated if using 3rd level spell slots for both inflict wounds plus the eldritch blast would equal 12d10 on a single turn?

Besides what Cyb3rM1nd said - my question would be: How are you planning on using 3rd level spell slots as a Fighter(2) + Warlock(3) + Sorcerer(3)? You'll have 2 level 2 Pact Magic spell slots from Warlock and the Sorcerer will have 4 1st and 2 2nd. So no 3rd level spell slots.

1) You can't cast Eldritch Blast as a bonus action and then cast anything else that turn except a cantrip.

PHB:

A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven't already taken a bonus action this turn. You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

2) You shouldn't have anything higher than second level slots at that level. Warlock 3 gives you two 2nd level slots. Sorcerer 3 gives you four 1st and two 2nd.

So you can quicken Inflict Wounds with a 2nd level slot doing 4d10. Then cast Eldritch blast doing 2d10. Then action surge and cast Eldritch Blast again doing 2d10. For a total of 8d10. If you stook Agonizing blast, you could also get your charisma modifier added on four times. Since you never got an ASI, we'll assume it is +3.

So if everything hits, that's 8d10 + 12

Familiars have to use their reaction to transmit a spell, so you can only transmit one spell through them per turn.

Knew I must have missed something, ie the stuff on bonus action spell casting & how multiclassing spell slots work lol, thanks all for the quick response's