The GCD of given numbers is 1.
Step 1 : Find prime factorization of each number.
$$\begin{aligned}4 =& 2\cdot2\\[8pt]11 =& 11\\[8pt]23 =& 23\\[8pt]33 =& 3\cdot11\\[8pt]49 =& 7\cdot7\\[8pt]23 =& 23\\[8pt]\end{aligned}$$(view steps on how to factor 4, 11, 23, 33, 49 and 23. )
Step 2 : Put a box around factors that are common for all numbers:
$$\begin{aligned}4 =& 2\cdot2\\[8pt]11 =& 11\\[8pt]23 =& 23\\[8pt]33 =& 3\cdot11\\[8pt]49 =& 7\cdot7\\[8pt]23 =& 23\\[8pt]\end{aligned}$$Note that in this example numbers do not have any common factors.
Step 3 : Multiply the boxed numbers together:
Since there is no boxed numbers we conclude that $~\color{blue}{ \text{GCD = 1} } $.