Needs["MaTeX`"]

Fqs[η_,x_,y_]:=(1/2)((x/((x^2)+(η^2)))+(y/((y^2)+(η^2))))
FSRG[s_,x_,y_]:=((x+y)/((x^2)+(y^2)))(1-Exp[-((x^2)+(y^2))s])

Grid[
{{With[{η=1},Plot3D[Fqs[(1/(2(η^2))),x,y],{x,-5,5},{y,-5,5},PlotLabel->MaTeX["f_\\text{qs}(x,y) = \\frac{1}{2} \\left( \\frac{x}{x^2+\\eta^2} + \\frac{y}{y^2+\\eta^2} \\right)",FontSize->20],MaxRecursion->500,ColorFunction->"DarkRainbow",PlotTheme->"Scientific",PerformanceGoal->"Quality",AxesLabel->{MaTeX["x",FontSize->20],MaTeX["y",FontSize->20],None},BoxRatios->{1,1,1},ImageSize->Medium,BoxStyle->Thick,BaseStyle->Directive[16],ViewPoint->{Front,Top,Right}]],
With[{η=1},Plot3D[FSRG[(1/(2(η^2))),x,y],{x,-5,5},{y,-5,5},PlotLabel->MaTeX["f_\\text{SRG}(x,y) = \\frac{x+y}{x^2+y^2} \\left[ 1 - e^{-(x^2+y^2)/(2\\eta^2)} \\right]",FontSize->20],MaxRecursion->500,ColorFunction->"DarkRainbow",PlotTheme->"Scientific",PerformanceGoal->"Quality",AxesLabel->{MaTeX["x",FontSize->20],MaTeX["y",FontSize->20],None},BoxRatios->{1,1,1},ImageSize->Medium,BoxStyle->Thick,BaseStyle->Directive[16],ViewPoint->{Front,Top,Right}]]
}},Spacings->{0,0}]