Will I be able to hook up 2 esc and 2 servo motors and a gyro and LCD on arduino UNO or should I buy a mega or use 2 UNOs
Depends on the ESC's, servos, gyros and LCD.
Mark
Will I be able to hook up 2 esc and 2 servo motors and a gyro and LCD on arduino UNO
Using a spreadsheet or not pad and the Uno 328 chip pin out, start allocating resources. For example to drive an LCD in parsllel-mode requires:
LCD. Uno
Vcc +5
Vss/RW Gnd
DB4. D5
DB5. D4
DB6. D3
DB7. D2
Now, continue for other parts. If you run into a conflict with pins, research options - do not go fordward without resolving all conflicts before assigning another pin.
In the case of the display, you could opt for a serial LCD at a higher cost.
Point is, I cannot answer such questions because you are in control of the purchase process and most forum members WILL NOT do a cold design for the Op (that's you) so you need to start practicing doing the difficult work and use the forum to get you out if those difficult spots.
Do read the "stickies" about what members are required to provide for posting - they are simple rules to help everyone.
Ray