[Mauzen]

Make a global variable that stores if the gates is open or closed. Then you can check it after strcmp and open/close it

pawn Код:

new gateopen = 0;

...
public OnPlayerCommandText(playerid, cmdtext[]) 
{
    if(strcmp(cmdtext, "/gate", true) == 0) 
    { 
        if(IsPlayerInRangeOfPoint(playerid, 10, 1588.9812011719, -1638.0415039063, 14.952730178833)) 
        {                  
            if(!gateopen) {
                MoveObject(obj, 1588.9812011719, -1638.0415039063, 7.952730178833, 2.00); 
                gateopen = 1;
            } else {
                MoveObject(obj, 1588.9812011719, -1638.0415039063, 14.952730178833, 2.00); 
                gateopen = 0;
            }                 
        }
    return 1; 
    } 
        
}

I dont know which move opens the gate and which closes it, just swap them if it is wrong.

EDIT: I just noticed, that you do not need the IsPlayerConnected. If a player is not on the server, he cant type a command