With regards to something solid, would it still be the same?
Yes, the same phrase would apply to liquid, semi-solid and solid food items. The state of matter of the food does not affect the phrase.
How would you put "much" or "a lot" in a sentence – "I haven't given you much/a lot" or "I haven't given you much/a lot of soup/vegetables"?
In casual speech, I would simply leave the phrase hanging, without specifying the actual noun. Consider:
- "I haven't given you much."
- "I haven't given you a lot."
- "I haven't given you that much."
While all the above are valid, I would most-likely phrase like the last option—with emphasis on that—as it subtly delineates between the speaker's opposition to the listener's opinion that they have been given too much, and not giving as much for a specific reason (e.g. due to the listener being on a strict diet, or the cost/availability of the food).
- "I haven't given you much, because I know you are on a diet."
- "I haven't given you a lot, because I can't afford to."
I do note that injecting and emphasising that is still applicable to the above sentences but, in that case, it is more likely a passive apology (becuase you are unable to give more) than the encouragement to eat more:
- "[I'm sorry,] I haven't given you that much, because I know you are on a diet."
- "[I'm sorry,] I haven't given you that much, because I can't afford to."
If you felt that you needed to specify exactly what food you had deliberately reduced, I would also use many for countable food items. This gives you options, such as:
- "I haven't given you that much soup."
- "I haven't given you that much dal."
- "I haven't given you that much meat." (as per Eli786's answer)
- "I haven't given you that many vegetables."
- "I haven't given you that many peas."
...but you could substitute a lot, in most cases:
- "I haven't given you a lot of soup."
- "I haven't given you a lot of dal."
- "I haven't given you a lot of meat."
- "I haven't given you a lot of vegetables."
- "I haven't given you a lot of peas."