Let me make it clearer then, sorry.
I played the first Heist with Smart Approach, meaning you have to get the van and the gas canisters. I completed all three missions, including the Heist, on Gold.
If I replay the Heist, I can choose to go for the Loud Approach, where I'll have to get the Carbine Rifles. If I complete this little mission on Gold, does that then count towards to the 70 medals you need?