Minecraft: Give items depending on player's score

There is no way to insert a scoreboard value in a command in the way that you described it in your comments, but you can do it like this:

/give @a[score_amount_min=1] SOME_ITEM 0
/scoreboard players remove @a[score_amount_min=1] amount 1

These commands should be looped.
This gives all players with a score on the amount scoreboard one item until the counter reaches 0.

You might also want to tag players with a certain tag, so that you can control when the items are given.

/scoreboard tag add SOME_PLAYER givemeitems

Then you change the target selectors in the previous commands to: @a[score_amount_min=1,tag=givemeitems]

That should do everything you want.