At least enough to not die, and extreme carbohydrate restriction is probably not great for gainz.
As long as you are getting adequate fat to support basic bodily functions, your carbohydrate and fat intakes are largely irrelevant with respect to hypertrophy. Protein is really the only important nutritional driver of hypertrophy, as long as your total energy intake is sufficient to support muscle growth, that is, you are in a calorie surplus. If you are doing concurrent training (aerobic and strength training together), you might have to watch your carbs to be sure you're getting enough to support your aerobic training, otherwise, it isn't something to be too concerned about.
For more details on optimizing your macro distribution for bulking, see the "Macronutrient Distribution While Bulking" section of this article: Optimizing Bulking Diets To Facilitate Hypertrophy. There is some evidence discussed in this section about potential downsides of extreme carbohydrate restriction. Dr. Trexler concludes that section by saying:
As long as you’re meeting or exceeding the bare minimums for carb and fat intake, their exact ratio is pretty inconsequential while bulking, so you should feel free to eat in accordance with your preferences.
If you want to grow, eat enough protein (at least 1.3 g/kg body weight), consume enough total energy to be in a modest surplus, and have a piece of toast every so often.